Modus Operandi Definition Example Essay

latin phrases and expressions [edit]

latin terminology, origins, meanings, translations and usage examples

Below is a list of Latin terms which (to varying degrees) are still used in English.

Some of this Latin terminology is very common in general speech and written communications; other Latin terms are more rarely used, in specialized situations, notably for example in law, science, and education/academia.

Latin terminology, expressions and phrases feature widely in the English language. The modern meanings and usage, while evolved and adapted, mostly still generally reflect the original literal translations.

Latin is a regarded as a 'dead' language because it is not used as a main language in day-to-day communications and life.

Latin however remains very much alive as a highly significant language, especially in technical references.

Here are just a few examples of Latin terms which are used very widely in English, including some extremely common abbreviations:

  • ad hoc
  • alias
  • bona fide
  • e.g. (exempli gratia)
  • etc. (et cetera )
  • i.e. (id est)
  • N.B. (nota bene), and
  • P.S. (post script)

There are many more very familiar Latin terms in the listing below, together with the literal/original meanings, and modern usage examples.

For a 'dead' language, the resilience of Latin is extraordinary. Its resilience would be extraordinary were Latin a living language.

Latin is still taught to millions of students around the world, and will continue to be for a very long time to come.

Fundamentally this is because:

  • Latin is the (or a) main and most recent root language for many major world languages.
  • Also, for centuries, in fact for two millennia, Latin been a main language of scholarship and academia.

More specifically:

  • Latin has for many centuries been used widely in law. Law is crucial to governance and leadership, society and civilization, diplomacy and international relations, business, trade, and commerce, finance, the military, and therefore so is Latin.
  • Latin has for many centuries been the language of the Christian religion, notably of Roman Catholicism. Christianity became an empire of sorts, which in its own way for centuries effectively ruled most of the world.
  • Latin has for many centuries been a crucial language for all of the sciences, therefore Latin has been crucial also to innovation, invention, exploration, transport, discovery, medicine, health, anatomy, every human and animal condition, and life itself.
  • Particularly related to the above, Latin terminology remains the underpinning language of living things and the biological taxonomy which organizes our understanding of every living thing on the planet.
  • Latin, chiefly via French, had a significant influence in the development of the English language. The conventional English alphabet (along with those of the Romance languages) is known as the Latinate alphabet, because its origins are in ancient Latin. (The 'Romance' languages notably include Spanish, Portuguese, French, Italian, and Romanian.)
  • Latin phrases and words have entered (directly and unchanged) the English language, and many other languages too - and the words, rules and structures of Latin have determined - and continue to determine - the way that new words are created.

Latin is obviously vital for the operation of many fundamental professions and disciplines, and for the rest of us, Latin remains fascinating and helpful in the understanding of our day-to-day language, especially the Latin expressions and terminology which survive and arise in business, technical definitions, law, education, grammar, and science, etc.

Here is the listing of Latin terms, including some very common popular phrases, and lots of less common specialized, yet fascinating terminology:

list of latin terms, phrases, and expressions

Latin terms in the English language - technical, legal, popular, fascinating

Latin termliteral translationmeaning in use
abacustray/counting tableancient calculator
ab extra / intrafrom beyond/inside(legal terms) 'ab extra' refers to information from external sources (instead of self or mind) - 'ab intra' refers to information from the self or mind
ab origine / aboriginefrom the firstoriginal inhabitants, from the source, origin, etc - (derivation of the modern word 'aborigine')
ab iratofrom an angry manactions/words by an angry person - (a legal term, similar to 'in the heat of the moment')
ab ovofrom the eggfrom the beginning
absente reo (abs. re.)(with) the defendant being absent(legal term) - in the absence of the accused
a capite ad calcemfrom head to heelthoroughly/completely/from top to bottom - more loosely expressed 'from head to toe'
Achilles (Achilles heel)ancient Greek heroweakness - (a Greek word used in Latin - the metaphor refers to the legend of the hero Achilles, as a baby held by the heel and dipped into the river Styx by his mother Thetis to make him immortal, leaving his heel vulnerable, such that when shot there by an arrow he died, hence the 'Achilles heel' or simply 'Achilles' is a person's main weakness)
acta est fabulathe drama has been acted outit's all over/it's finished/the end
A.D. (anno domini)in the year of the Lorddenotes that the year is since Christ's birth in the Julian and Gregorian calendars - contrasting with B.C. (Before Christ), which signifies years 'Before Christ', which are counted backwards - there is no zero year
ad hocto/for thisimprovised/devised/applied spontaneously or purely for the purpose ('just for this')
a fortioriwith strengthall the more so, with greater reason
ad hominemto the manpersonally directed - (as when criticizing someone)
ad infinitumto infinityendlessly/for ever/without limit
ad interim (ad int)for the meantimein the interim/meantime/temporary/stand-in/
ad lib (ad libitum)with freedomfreely, improvised, spontaneously created - now most commonly an instruction or freedom to 'improvise' in performance, communication
ad litteramto the letterprecisely/according to the 'letter of the law'
ad nauseamto (produce) sea-sicknessto the point of causing nausea/unbearably tedious
a priori / a posteriorifrom what comes before/ after(these terms mainly refer to philosophical or mathematical assertions) - an 'a priori' fact is self-evident, known without need of direct specific experience/evidence (for example 'snow is cold') - an 'a posteriori' fact is based on observed evidence or experience, etc (for example snow fell in Ireland on [a particular date])
ad referendum (ad ref)to/for referringfor further consideration (elsewhere)
ad remto the thingto the matter in hand/directly relevant
adsumI am herepresent (formal answer to a rollcall)
aegrotathe is illdoctor's note - medical excuse/qualification awarded when exams are missed due to sickness
Aesopwriter of fables(see Aesop's Fables)
aetatis (aetat or aet)aged (number of years)aged... or 'of the age...' (precedes the age of someone/something)
affidavithe/she has declared under oatha sworn statement made voluntarily by a person, recorded by a qualified person, usually for legal purposes, such as admission in a court case
agenda (agenda sunt or agendum est)things that must be moved forwardlist of items for a meeting, order of discussion, set of aims, motivational factors - agenda now has a wide range of meanings, after initially referring to a meeting schedule
Aiax/Ajaxhero of Trojan Wara metaphor for size and stength
AlbionBritainthe ancient Greek word for Britain
alia iacta est / iacta alia estthe die is castthe die is cast - beyond the point of possible return, fully committed come what may - see the die is cast and cross the Rubicon in cliches origins - the phrase is attributed to Julius Casear, 49BC, on his invasion of Rome from Gaul - as with many other Latin phrases the 'i' of iacta is alternatively a 'j', so that the word was/is jiacta (although some say Caesar spoke this phrase in Greek anyway..)
alias dictus (alias)at another time calledotherwise known as/also known as/aka
alibielsewherea submission or claim, typically supported by proof/evidence, that an accused person was at a different place from the scene and time of a crime
alieni generisof a different kindof a different kind/of another type
alphaA (the letter)denotes the first of something, for example alpha-male (dominant male), or alpha-test (the initial release of technology/software among developers, prior to finalizing specification/features and beta-test, being final testing among users)
alma maternourishing motherone's college or university
alter egoother self/other Isecondary personality/other self/trusted friend
alumnusnursling/foster childgraduate or student of educational institution (alumna, alumni, alumnae are respectively female, plural and female plural)
a mensa et torofrom table to bedlegal separation (divorce)
amicus curiaefriend of courtan objective or neutral advisor in legal process
amore carenslove withoutloveless
amor vincit omnialove conquers alllove conquers all
amor proximilove one's neighbourlove thy neighbour/love your neighbour (US neighbor)
anno Dominiyear of our Lord(AD)/since BC (before Christ)
annus horribilis/terribilis/ mirabilishorrible/terrible/ wonderful year(different dramatic ways to refer to good/bad years)
ante bellumbefore warpre-war (which war depends on context/situation)
ante meridiem (a.m.)before middaybefore noon/morning/AM/am
apexsummit, crownpeak, top, pinnacle
appendixsupplementsupplement (extra document/body of text/information) - separately in anatomy an obsolete sac in humans connecting to large intestine - from appendere, 'hang upon'
aqua vitaewater of life(metaphorical reference to) a local/national/special drink - (used variously to refer to different drinks, typically local or national or particularly enjoyed from the speaker's view, commonly for example: wine, whisky/whiskey, brandy, ale, etc
arbiterjudge, witnessjudge, controller, arbitrator, umpire
ars gratia artisart for art's sakeart for art's sake - art that is free from non-artistic pressures/aims (e.g., profit, politics, etc)
Artium BaccalaureusArts BachelorBachelor of Arts/AB/BA/(university degree)
Artium MagisterArts MasterMaster of Arts/MA/AM/(higher university degree)
aureo hamo piscarito fish with a golden hook'money talks'/money gets results
Aurora Borealisgoddess of the northern dawnthe 'Northern Lights' atmospheric display, at certain times in the night sky far north - Aurora is the Roman goddess of the dawn - Borealis meaning northen in Latin is taken from the Greek Boreas, god of the north wind - Aurora Australis is literally 'goddess of the southern dawn', and refers to the 'Southern Lights' (being the equivalent phenomenon in the southern hemisphere) - australis means southern in Latin
australissouthernthe origin of the name Australia - from 'terra australis', southern land
ave Mariahail Maryhail Mary
a vinculo matrimonii(free) from the bond of marriagecomplete divorce (sometimes abbreviated to 'a vinculo')
betaB (the letter)notably 'beta-test', referring to the external release (to users) of machinery/technology/software (of completed specification/features) in the final stage of testing - compared with 'alpha-test' which is controlled release among developers aimed at fixing the features/specification prior to beta release
bis in die (b.i.d.)twice in a daymedical abbreviations - (for example instructions for taking tablets)
bona fidegood faithin good faith/honestly/genuine/real
cadit quaestiothe question fallsargument collapses/the central legal argument has collapsed (so move on)
caeteris (ceteris paribus)other things being equalall things equal/other things being equal
campusplain (grassland)university and its grounds
carpe diemseize the dayenjoy the opportunity/make the most of the chance - (the full quote is 'carpe diem, quam minimum credula postero' = 'enjoy today, trusting little in tomorrow' - from Horace's Odes)
casus foederisfall (action) (due to) league/alliancesituation causing action under a treaty
causa sine qua nona cause without which nota necessary condition
cave/cave canembeware/beware of the dogbeware, caution, take care, attention/beware of the dog
caveatlet one bewarea stipulation, condition, warning, exclusion, limit, etc - typically in formal contracts, also in verbal agreements
caveat emptorlet the buyer bewarebuyer beware/responsibility is with buyer
caveat venditorlet the seller bewareseller beware/responsibility is with seller
cerebrumbrainfront part of brain - considered advanced compared with early human brains and additional to animal brains - hence cerebral refers to intellectual rather than emotional or physical thought/behaviour/effect
certiorarito be made certaina writ issued by a higher court for documents from a lower court for the purpose of reviewing the lower court process/decision
cetara desuntthe rest are missingparts of the (written/created) work have not been found (despite research)
ceteris (caeteris paribus)all other things being equalassuming that no external factors alter the central question/point, conditional on there being no effect from variable external elements - (a qualifying statement establishing fixed conditions around a proposition, to enable a firm argument to be made)
citius altius fortiusfaster higher strongermotto of the modern Olympic games  
confer (cf.)comparecompare (with)/see also (as appears widely in dictionaries, etc)
circa (ca. or c.)aroundabout/approximately/roughly (referring to a quantity, date, time, etc)
codextreetrunk/wooden blockmanuscript/code of laws
cogito ergo sumI think therefore I existI think therefore I exist, or I think therefore I am - (originally recorded by French philosopher René Descartes, 1596-1650 - in Discourse on the Method, part IV, 1637-44, written mostly in French but with parts in Latin)
coitus interruptusgoing together interruptionwithdrawal before ejaculation (for contraception or other reason)
coitus more ferarumsex in the way of wild beasts(medical/humorous reference to) 'doggy style' sexual intercourse - historians assert that the expression in its Latin form was used in ancient Rome
compos mentisof sound mindin full possession of mental powers, sane (cf. non compos mentis) 
con (contra)againstagainst
coniunctis / conjunctis viribuswith united powers(acting) with united powers (towards a commonly agreed aim)
consensusagreementagreement (among a number of people) - (note that this word is related to the English word consent, not to census, which misunderstanding often produces the misspelling 'concensus')
consensus adaciumagreement of audacious/rash mena conspiracy
consensus facit legemconsent makes law(a principle that) any agreement between parties may be legally binding provided it does not violate law
consensus gentiumagreement wide/generalwide agreement/generally accepted belief or views
consensus omniumagreement of allagreement of all/general agreement
cornu copiaehorn of plentycornucopia/abundance (from various Greek legends, most popularly: The baby Zeus, hiding from his baby-eating father Cronus, was suckled as an infant by a goat/nursemaid, Amalthea. Zeus, having the strength of a god, accidentally broke off one of Amalthea's horns, which he then endowed with the power to produce unending nourishment (and anything else desired) for its owner
corrigendaitems to be corrected(draws attention to) corrections required in a manuscript before publishing
cui bono/malo?who will gain/lose?who stands to benefit/lose (from a particular action/situation)? - expressions in criminal investigation or other speculation - in attempting to reveal motive/responsibility
cum grano saliswith a grain of salttake (a comment) with a grain of salt/add a note of caution to a comment (in Roman times and more recent history too, salt was very valuable and symbolic of something not to regard lightly - Roman soldiers were paid in salt - salarium - hence the expression 'worth his salt' (someone is worthy of his/her wage)
(summa/magna) cum laudewith (greatest/great) praisetraditionally highest/2nd, and 3rd grades in a US university degree
curriculum vitaethe course of (one's) lifea resume or job/personal history/(commonly abbreviated to CV)
cursorrunner, courierpositional marker on an electronic display
de bonis asportatiscarrying goods away old legal term for larceny, which has largely been superseded by the term theft
de bono et maloof good and bad(of a decision) come what may/for good or bad/'whatever'
decimusa tenthfrom which 'decimate' originates - strictly
de dicto / de reof (the) word / of (the) thing(technical clarification of the nature of a statement so as to differentiate) - the wording of the statement/(as distinct from) the thing that the statement refers to - these are two contrasting terms used in philosophical discussion/works differentiating between the form of the statement and what the statement refers to - (while quite subtle and technical, these two terms are useful in highlighting the difference between the qualities of a statement as distinct from the truth or otherwise of what the statement seeks to convey) - for example many children's statements can be criticized 'de dicto', while being brilliant 'de re' - (note that there are more complex applications of these terms)
de die in diem (diem ex die)from day to daycontinuously/day in, day out/without a break
de factoof factin reality/in practice (especially contrasted with something which exists in in a lesser way theory or in law, see de jure/iure)
dei gratiaby the grace of godby the grace of god (traditionally implying a divine right, such as a monarch's title/status)
de jure (de iure)according to lawexisting legally/legally sanctioned/legally approved
delineavitdrawn by(of a work of art) created by (followed by the artist's name)
delerium tremenstrembling deliriumthe DTs/bodily shaking caused by nervous disorder from alcohol abuse
denarius/denari/denariismall common Roman silver coinin English money history 'D' or 'd' for denarius came to denote pence in pre-decimalisation pounds shillings pence (LSD) - (the denari equated loosely to a labourer's daily pay) - the L and S in LSD also originated from ancient Latin, 'libra' and 'solidus nummus'
deo volente (d.v.)god willinggod willing - if possible
deus ex machinagod out of a machineperson/thing/event which suddenly unexpectedly resolves a problem - also a contrived resolution of a plot in a dramatic work such as a play or film
de nihilo nihilfrom nothing comes nothingnothing comes from nothing/don't expect something to come from nothing
de novoanewanew, refreshed
deperire / depereohopelessly in love(to be) utterly/helplessly/hopelessly in love (with someone/something)
divide et imperadivide and ruledivide your opponents to defeat them (a maxim adopted and popularized by Machiavelli)
doce ut discaslearn by teachingteach in order to learn
docendo discimuslearning by teachingwe learn something by teaching it to others
doctus cum librolearned with a bookhaving knowledge without practical experience
Domine, dirige nosLord, direct usLord/God, direct us (God is our guide) - traditional official motto of London
Dominus vobsicum/Dominus tecumGod be with you (plural)/God be with you (singular)God be with you (all)/God be with you (to an individual) - a traditional way to say farewell or goodbye
dramatis personaethe persons of the dramacast of characters (in a play or film, or situation, etc)
dum spiro sperowhile I breathe, I hopewhile there is life in me I can still hope
dum tacent clamantthough they are silent they cry aloudtheir silence speaks volumes (usually referring to silence being an effective admission or indication of guilt or fault)
dum vita est spes estwhile there is life there is hopewhile there's life there's hope
dura matertough mother(medical/biological term for) the outer membrane of the brain and spinal cord - the Latin term is itself derived from an earlier fuller Arabic term, loosely 'thick mother of the brain'
ecce homobehold the manconsidered by advocates, and represented by artists, of biblical history, as the words of Pontias Pilate in presenting Jesus Christ to the crowd after flagellation prior to crucifixion
ecce signumbehold the signlook at the proof - examine the evidence - the proof is in front of you, so look at it
e contrarioon the contraryon the contrary - actually, the opposite is true
editio cum notis variorumedition with various notesa technical academic/scholar term referring to a version of text which contains different interpretations and notes and comments from experts
editio princepsfirst editionthe first printed edition (of a book especially)
e.g. (exempli gratia)for the sake of examplefor example, or for instance
emeritusa soldier who has served his time honourably/honorably and earned his dischargedenoting the title holder (for example a professor) has retired and retains the title (plus the word 'emeritus') as a mark of having served with distinction - the original meaning derives from soldiers in the Roman army, from the verb 'mereri', to earn
emerita(female form of emeritus)(a relatively modern adaptation of the conventional emeritus male/general form above)
e pluribus unumone out of (from) manyone (big thing) made from many smaller parts - motto of the USA
ergothereforetherefore - and so it follows that.. (linking a cause or situation with a result or conclusion)
errare humanum estto err is humanpeople occasionally naturally make mistakes - popularized by Alexander Pope's 'An Essay on Criticism' which stated 'To err is human; to forgive, divine' - this is an acceptance of human weakness
et al (et alii/et aliae/et alia)and others (abbreviation - male/female/neuter full versions)and other men/women/factors (et al is the abbreviation - et alii is 'and other men'; et aliae is 'and other women'; et alia is 'and other things' - traditionally speech etiquette suggested that "...educated people do not ever actually say 'et al', instead they say 'and others'...")
etc (et cetera)and the restand so on - typically replacing potentially additional items in a listing of similar factors
et nunc et sempernow and for everfrom now on
et seq (et sequentes/sequentia)and the following...usually abbreviated 'et seq' - (or seqq, sqq)
et tu, Bruteyou also, Brutusrealization, acknowledgment, and accusation that an apparent trusted friend or ally is actually an enemy - the expression was popularized by Plutarch's and Shakespeare's telling of the killing of Julius Caesar by conspirators including his previous friend Brutus
et ux (et uxor) / et virand wife / and husband(legal terms meaning) and wife / and husband
ex animofrom the heartsincerely
ex astris scientiafrom the stars, knowledge'From the Stars, Knowledge' - a contrived retrospective Latin expression created as the maxim of the Starfleet Academy in the film/TV franchise Star Trek.
ex cathedrafrom the chairwith authority - refers to statements made by experts, or claimed to be (cathedra referred to a teacher's chair before it more famously meant the Pope's chair)
excud (excudit)he/she who struck this (made by)made by... a traditional printer's or engraver's term preceding the name of the creator/maker/writer
ex dolo malo (ex dolo malo non oritur actio)an action (in court) does not arise from frauda Latin legal term equating to 'fraud' - deriving distortedly from the full original sense that a court action cannot be viable if based on a fraud
excelsiorever upwardever upward
exeatlet him/her go forthpermission to be absent - traditionally an exeat granted permission for a priest to leave a monastery - the term also extended to absence from a university
exempli gratia (e.g.)for the sake of examplefor example, or for instance
ex faciefrom the facea legal term used typically when referring to an obviously unreliable document - the term in this context equates to 'obviously' or 'needing no further examination'
ex gratiaout of goodnesspayment or reward given freely without obligation
exithe/she goes outa single actor leaves the stage
ex librisfrom the booksfrom the library of... (owner's name)
ex mero motuout of pure simple impulsespontaneously - (implication being no external influence)
ex nihilo nihil fitnothing comes from nothingnought comes from nought -
ex partefrom a partyfrom one side only - only one side is represented at a legal hearing (the other side is absent)
ex pede Herculemfrom the foot, a Herculesfrom a small sample the whole thing can be estimated - an early principle of extrapolation or projection, said to derive from Pythagoras' calculations in estimating the size of Hercules from his foot size, in turn inferred from the scale of the Olympia stadium
experto crediteexperience gives credibilitytrust one who has the experience - from experience a person has credibility
ex post factofrom what happens afterwardsknowledge or law after an event applied retrospectively to the event - similar to 'with the benefit of hindsight', or the sense of 'knowing now what we did not know then'
exuent / exuent omnesthey go out / they all go outthey leave the stage - stage direction terminology
ex ungue leonemfrom a claw, the lionfrom a small sample the whole thing can be estimated - equating to ex pede Herculem
ex uno disce omnesfrom one deduce allfrom a small sample the whole thing can be estimated - equating to ex pede Herculem
facta non verbaactions speak louder than wordsactions speak louder than words - judge by deed not what is said
fecit (F.)he/she made (it)made by... (creator's name) - traditional term used by artists/makers - separately F may stand for 'filius', meaning 'son'
felo de sefelon of himselfsuicide
festina lentehasten slowlymore haste less speed
fiat luxlet there be lightlet there be light - (alternatively represented by the rarer Latin 'lux sit')
Fidei Defensor (Fid Def or fd)Defender of the FaithTitle first given to Henry VIII of England by Pope Leo X in 1521. Removed by Rome c.1530 after Henry divorced catholic Catherine of Arragon, and reinistated later in his reign as defender of the protestant faith. The title endures to modern times, shown in official references and on British coins, usually abbreviated FD.
fide et amoreby faith and loveby faith and love
Fidei Defensor (FD)Defender of the Faithtraditional additional title of English/British monarchs, given by the Vatican - often abbreviated to FD
floruit (fl)he/she flourishedwhen a historical character was most productive/active - used in biographical information, especially if birth/death dates are unknown, the 'fl' symbol appears with the year(s) of his/her prominence
fons et origosource and originthe source and origin (of something)
fronti nulla fidesappearance is not reliableappearances can be deceptive - or 'don't judge a book by its cover'
fugit horaflies the hourtime flies - time passes quickly
genius locispirit of the placethe atmosphere of somewhere including its influence on visitors
grammatici certantgrammarians dispute (are disputing)experts are discussing (a case/matter/dispute) - this refers to situations that are subject to official review before a decision or resolution is made
gratias tibi agothank youthank you
habeas corpus(you) shall have the (arrested person's) body in courta legal order for an arrested person to attend court, especially from the accused standpoint, so that unless lawful grounds are offered for detention then the person must be released
hic et nunchere and nowhere and now - immediately, forthwith -for example when demanding immediate payment
hic jacet / iacethere lieshere lies (the body of..) - a tombstone term
hic situs estthis is the placethis is the place
hic sunt dracones / leoneshere be dragons/lionsunchartered territory - these are very old references to unchartered territories, used on maps, and since then popularized in dramatic works
hoc annoin this yearin this year
hoc locoin this placehere
honoris causafor the sake of honour/honordenotes an academic or other qualification given on merit, rather than by official examination
hora fugitthe hour fliestime passes quickly - time is pressing
hora somni (h.s.)at the hour of sleepat bedtime - (medical term)
horribile dictuhorrible to saya warning before telling an awful or upsetting description/report
iacta / jacta alea estthe die is castthe die is cast - the decision/commitment is made and irreversible (see the die is cast in cliches origins)
ianuis / januis clausiswith closed doorsbehind closed doors (referring to a legal hearing or court or meeting)
ibid. (ibidem)in the same placein the same source referenced in the previous entry - (an academic referencing mechanism to save space and unnecessary repeating of the same detail when citing sources)
id. (idem)the samethe same author (as previously referenced) - an academic space-saving device used in citing authors
(i.e.) id estthat is (to say more clearly...)in other words, in more detail, or to say more clearly and fully.. (this very common term is often misused in place of 'e.g.' (for example), whereas 'i.e.' means that clarification of a previous point is to follow
in medias resinto the middle of thingsthe way a dramatic work such as a play or story begins
INRI (Iesus [Jesus] Nazarenus Rex Iudaeoreum [Juaeoreum])Jesus of Nazareth, King of the JewsJesus of Nazareth, King of the Jews -
ignorantia legis neminem excusatignorance of the law does not excuseignorance of the law is no defence/defense for breaking the law
ignorantia non excusatignorance does not excuseignorance is not an excuse (for wrong-doing) - the implication is that a person's moral code should not have to rely on specific instruction to avoid wrong deeds
in absentiain (one's) absencedenotes action against or award to someone in their absence, for whatever reason - for example criminal convictions and academic awards
in aertenumfor everfor ever, in perpetuity
in articulo mortisin the grasp of death(a statement made) at the point of death - traditionally statements made 'in articulo mortis' have at times been considered additionally believable because the person had nothing to gain at that stage from lying - alternative to 'in extremis'
in camerain a chamberin private - typically court/legal proceedings which exclude public and press
incipithere beginsdenoting the start of old/ancient texts
(bis/ter/quater) in die (b.i.d./t.i.d./q.i.d.)(twice/three times/four times) in a daymedical abbreviations - (for example instructions for taking tablets)
in dubio (in dubio pro reo )in doubt, for the accusedthe defendant has the benefit of the doubt - innocent until proven guilty
in essein beingactually existing - contrasting with 'in posse'
in extensoin fullword for word, fully and entirely - referring to a text or paper of some sort, emphasize there has been no edit/removal
in extremisin endat death - at the point of (a person's) death - alternative to 'in articulo mortis' - mostly significant in assessing reliability of statements made by the deceased in relation to a case
in fine (i.f.)in the endat the end of (a stated reference or page, etc)
in flagrante (in flagrante delicto)in flaming crime(caught) in the act (of wrong-doing) - often referring to the discovery of sexual liaisons and adulterous relationships
in foroin forumin court (legal term) 
infrabelow(see note) below - directs readers to explanatory detail below the item concerned, often preceded with 'vide' (see) - infra is also a prefix meaning below, under, beneath, 'sub', lower than, etc (infrastructure, infrared, etc) - broadly contrasting with 'ultra' (beyond/to extreme degree)
infra dignitatem/infra digbelow dignitybeneath (a person's) dignity or normally expected standards, referring to actions or behaviour/behavior
in futuroin futurein the future
in illo ordine (i.o.)in that orderrespectively
in limineon the thresholdabout to happen
in loco parentisin place of a parentguardianship or responsibility for a minor
in media resinto the middle of thingsintroductory statement before telling a story, or a the start of a play
in memoriamin memoryin the memory of - (typically an inscription on a memorial stone or other material)
in ovoin the eggimmature, undeveloped
in pectorein the breastin secret
in perpetuumfor everforever
in plenoin fullin full, complete (typically referring to a payment)
in possepotentiallypotentially - contrasting with 'in esse'
in propria personain personin person, personally
in re (re)in the matter ofregarding - alternatively and more technically in legal matters (the full form 'in re') means that a case is uncontested 
in saecula saeculorumfor ages of agesfor ever and ever
in sein itselfin itself (an alternative to 'per se' - by itself)
in situin placein its natural location (contrasting with 'in vitro' - in glass [a glass test-tube])
instante mense (inst.)in the present month(substitute term for whatever the current month is - (for example "...your letter of 5th inst. refers...) - ult = last (month); prox = next (month)
in statu quoin the state in which(slightly different to 'status quo' - in statu quo refers to a situation at a specified time, relative to a subsequent or prior different situation, rather like saying 'in statu quo [the situation/condition/state] in the 1970s...' or 'in statu quo [the situation/condition/state] before the business was floated...' )
inter aliaamong other thingsamong other things, included in other considerations
inter aliosamong other peopleamong other people, included within a wider groups of people
inter nosbetween usbetween us, among ourselves, between ourselves
inter paresbetween equalsbetween our peer group (of a discussion or circulated notes)
inter sebetween themselvesbetween them, among themselves
inter vivosbetween the living(for example referring to transfer of property) between two living people, (as distinct from a transfer following someone's death)
in totoin totalcompletely, wholly, fully, altogether
in vino veritasin wine the truthpeople speak freely when under the influence of alcohol, alcohol/wine loosens the tongue
in vitroin glassin a test-tube, (developed) in a laboratory or artificial environment - contrasting with 'in situ'
in vivoin life(developed/experimented) in a living thing/organism - contrasting with 'in vitro'
ipsissima verbathe exact wordsverbatim - word for word - (referring to quoted remarks)
ipso factoby that factas a direct immediate consequence of that fact/act
justitia omnibusjustice for alljustice to all, be fair to everyone
lapsus linguaeerror of tongueslip of the tongue, verbal mistake
lapsus memoriaeerror of memorymistaken memory, faulty recollection, remembered wrong
lex locilaw of the placelaw of the land, local jurisdiction
lex non scriptalaw not writtenunwritten law, common law
lex scriptalaw writtenformal written statute
libra (lb and £)balance, set of scales, poundthe origin of the £ pound sterling symbol and pound weight (lb) symbol - libra, meaning a set of weighing scales, (which separately became a sign of the Zodiac) meant a pound in weight, and (via late Middle Ages English) a pound in money (weight and money were directly related), being the origin of the traditional pre-decimalisation 'L' denoting the £ pound-sign in LSD (pounds shillings pence) - the S and D symbols were also derived from ancient Latin money terms - 'solidus nummus' and 'denarius' - separately libra means book (hence 'library')
licetit is allowedit is allowed/permitted/licensed
lis sub judice/iudice (sub judice)lawsuit before the judgecase not yet decided
loco citato (loc. cit.)place cited (work)in the work/place/source previously referenced - (a referencing note used by scholars/writers/academics, to avoid repeating entire sources)
locum tenens (locum)place holding (person)deputy, substitute, temporary replacement (for example of a doctor)
locus classicusplace classic (work)authoritative work/source/extract/text, the generally most highly regarded source (a referencing note referring to a work considered highly authoritative)
locus delectiplace (of) crimescene of the crime, crime scene
locus in quoplace in whichplace in question (where the incident in question happened)
loquitur (loq.)he/she speaks(script note that) a person speaks - (a dramatic/stage direction)
lucri causagain causefor the sake of (monetary) reward/gain/enrichment - in hope of financial reward - 'profit driven' - motivated by money
magister artium (M.A.)master of artsMaster of Arts - university degree - also abbreviated reversed, AM 
magna cum laudewith great praisesecond honors/honours university degree (see cum laude)
magnum opusgreat workthe/a major work of a creative (writer, composer, etc)
majorgreatgreat, significant - major/maior is the Latin comparative of magnus, great
mala fidebad faithin bad faith - fraudulent - (contrasting with 'bona fide')
male captus, bene detentuswrongly captured, properly detained(controversial legal principle asserting that) improper arrest should not prevent proper detention and trial - (the principle is not universally enforceable)
malesuada famespersuaded to evil by hungercrime (that is) produced by hunger - (see Maslow's Hierarchy of Needs)
malo animowith evil intentequating and evolving to the legal phrase 'with malice aforethought'
malum in se / malum prohibitumwrong in itself / wrong according to law(legal terms differentiating that something is) inherently wrong / wrong in law - (for example an ambulance which jumps a red light en route to an accident is committing an offence which is 'malum prohibitum', but not 'malum in se')
mandamuswe command(a legal writ) instruction from a higher court to a lower court
manu propria (m.p.)(signed) by own hand(old rare term indicating that a signature was made) by the signatory's own hand - (where a signature is missing, or a printed document contains a copy of a signature)
mea culpaby my faultI am responsible for the problem - acknowledgment of guilt or blame
mediamiddle (plural)media now means various things in English, notably the news and information industries ('mass media'), and ways or materials for communicating in the broadest sense - the origin is Latin, from the singular word medium, meaning middle, which caused the word to evolve in English to refer to an agency or means of doing something (the sense of a body or mechanism between two parties, acting as a tool, enabler, conduit, translator, communicator)
medicinae doctor (M.D.)doctor of medicinedesignation of a university degree and doctor of medicine, a general practitioner (GP)
membrum virilemember male (reproductive organ)polite term for penis
memo (memorandum est)it must be remembered (that..)a written/audio or other note - (to self or more commonly others in a work group) - a 'memo' was the pre-internet age standard quick recorded paper communication between work people, typically from a manager to subordinates, or fellow-managers or superior staff - before desktop computers, memos were typically hand-written or dictated by managers and typed and copied using carbon paper (pre-1970s), later photocopiers (pre-1990s), by typists/secretaries - these intensive production methods ensured that old-style paper memos were generated and circulated in relatively tiny volumes compared to the billions of modern emails
mens sana in corpore sanosound mind, sound bodysound in mind and body
mirabile dictu/visuwonderful to relate/seeamazingly (to tell/see)
mobile vulgusmovable public


Scientists have long played a role in examining deviant behavior in society. ``Deviance behaviour'' is a term used by scientists to refer to some form of ``rule-breaking'' behaviour (Holdaway, 1993). It can be the behaviour of violating a social norm or the law. Criminal behaviour is also a form of deviance, one that is defined as the breaking of legal rules. Nevertheless, there is a difference between deviance and crime. Deviance involves breaking a norm and evoking a negative reaction from others. Crime is a deviance that breaks a law, which is a norm stipulated and enforced by government bodies (Holdaway, 1993). However, crimes negatively affect society. Therefore, law enforcement authorities take necessary actions to mitigate crimes in an environment where high crime frequencies are observed each year. In this exercise, the application of technology for crime analysis is being widened in the world. Locard's exchange principle states that every contact of the perpetrators of a crime scene leaves a trace. The perpetrators will both bring something into the scene and leave with something from the scene (Chisum & Turvey, 2000). However, the cognitive abilities of criminals will always make them minimize their risks of apprehension by conducting the perfect crime and maximizing their gain (Paternoster & Bachman, 2001). Modus operandi or method of operation such as preparation actions, crime methods and weapons are frequently used in criminal profiling because the past crime trends show that, after criminals get used to a certain method of operation, they try to use the same modus operandi in committing his/her next crime (Palmiotto, 1988).

The criminals develop a set of actions during the performance of a series of crimes which we refer to as ``modus operandi'' (MO). MO is developed with the crimes he/she commits and the nature of trying to stick with the developed MO that has worked throughout the previous crimes (Douglas & Douglas, 2006). In any criminal career, the MO happens to evolve, no matter what the circumstances. Also, it is a common behaviour that serial offenders tend to exhibit significant behaviour known as his/her signature. Therefore, MOs of criminals play a major role in investigating crimes (Douglas & Douglas, 2006). It is a known fact that features such as criminal signature and physical appearance are used in crime investigations in almost all the police departments around the world. Sri Lanka police also use MOs of criminals to identify the suspects who have conducted crimes. Currently Sri Lanka Police use a manual crime recording and investigation system. This manual system has many problems such as data redundancy, inefficiency, tediousness, inability to support crime investigation and many other problems which are associated with a conventional manual system. To overcome these problems, a web-based framework was proposed with geographical information support containing a centralized database for crime data storage and retrieval, named SL-CIDSS: Sri Lanka Crime Investigation Decision Support System (Chamikara et al., 2015). The proposed system accompanies a collection of data mining algorithms which effectively support the crime investigation process. Fuzzy based binary feature profiling (BFPM) for modus operandi analysis is one novel algorithm which is integrated with the system to provide an effective way to find the similarity between crimes and criminals.

According to the penal code of Sri Lanka first enacted in 1882 and amended subsequently several times in later years (The `Lectric Law Library, 0000), Sri Lanka police classifies crimes into two categories: Grave crimes and Minor offences. Until 2014, grave crimes were classified under 21 crime categories and in 2015 another 5 new crime categories were introduced, making it 26 categories of grave crime types. Kidnapping, Fraud or mischief causing damage greater than 25,000 rupees, Burglary, Grievous hurt, Hurt by sharp weapon, Homicide, Rape, Robbery, Cheating by trust, Theft are 10 of the most frequent crime types. To identify the patterns involved in crimes, a collection of subtypes were identified under these 26 crime types. These subtypes have been created mainly for the purpose of modus operandi analysis. Most frequent behaviors of criminals/crimes are considered as crime subtypes. When a crime is logged in the Grave Crime Record (GCR) book, it is classified under one of the 26 main categories. But, under the section of ``nature of crime'' in the GCR book, the police officers record the flow of the crime incident including the subtypes.

A subtype is a sub category of one of the main crime types. For investigation, the nature of the crime is broken into subtypes and flows according to their frequency of occurrence and uniqueness. These sub categorizations have been introduced mainly to minimize the broadness of main type and to improve clarity. Figure 1 depicts the relationship of the subtypes and flows where there can be a flow of events to a crime recorded as one of the 26 main crime types. For the simplicity and easy handling of data, the investigators have provided subtype codes and flow codes. The flow of events provides a modus operandi which is most of the time unique to an offender. Each subtype is provided with a code under the main type, to make the crime investigation process easier. For example, ROB/S001 denotes a subtype that is Highway robbery; here ROB denotes the main type under which the corresponding subtype appears. In this case, it is Robbery. Crime types are further subdivided into sub types to make the analysis and processing simpler. In this manner, crime subtypes and flows have been identified under all the 26 crime types. The space for adding more subtypes and flows under these crime types exists. A new subtype or a flow is introduced to a particular main crime, if the same subtype or the flow happens to persist for a prolonged time.

This paper proposes a novel method of criminal profiling using modus operandi which can be used to identify associations between crimes and criminals. The method is based on a new technique named, ``binary feature vector profiling.'' Key relationships between a criminal and the previous convictions are analyzed using binary feature profiling and association rule mining techniques. Due to the impreciseness and vagueness of these extracted attributes, a fuzzy inference system is used in making the final decision. The newly proposed method was adapted into a classification algorithm in order to test its accuracy. An actual crime data set was used in testing the performance of the newly proposed method and it was compared against nine well-established classification algorithms using ten open data sets. The results confirmed that the proposed method produce competitive results compared to the other nine classification algorithms.

The rest of the paper is organized as follows. The Related work section presents a summary of the work that has been conducted on modus operandi analysis as well as a brief discussion on crime investigation using link analysis and association mining in general. The Materials and Methods section discusses the main steps of the newly proposed algorithm. Next, the Results and Discussion section provides a validation and performance evaluation of the newly proposed method along with a performance comparison with nine other classification algorithms. Finally, some concluding remarks and future enhancements are outlined in the Conclusion section.

Related work

Literature shows many methods which have been developed in the area of automated crime investigation. Our major concern has been laid upon the research carried out on crime investigation using association mining as our research considers on developing a model to find the associations between the criminals and the crimes depending on the modes operandi. Bennell & Canter (2002) have proposed a method to use statistical models to test directly the police practice of utilizing modus operandi to link crimes to a common offender. The results indicated that certain features such as the distance between burglary locations, lead to high levels of predictive accuracy. Bennell & Jones (2005) have tried to determine if readily available information about commercial and residential serial burglaries, in the form of the offender's modus operandi, provides a statistically significant basis for accurately linking crimes committed by the same offenders. Leclerc, Proulx & Beauregard (2009) have reviewed the theoretical, empirical, and practical implications related to the modus operandi of sexual offenders against children. They have presented the rational choice perspective in criminology followed by descriptive studies aimed specifically at providing information on modus operandi of sexual offenders against children.

Clustering crimes, finding links between crimes, profiling offenders and criminal network detection are some of the common areas where data mining is applied in crime analysis (Oatley & Ewwart, 2011; King & Sutton, 2013; Borg et al., 2014). Association analysis, classification and prediction, cluster analysis, and outlier analysis are some of the traditional data mining techniques which can be used to identify patterns in structured data. Offender profiling is a methodology which is used in profiling unknown criminals or offenders. The purpose of offender profiling is to identify the socio-demographic characteristics of an offender based on information available at the crime scene (Mokros & Alison, 2002; Canter et al., 2013). Association rule mining discovers the items in databases which occur frequently and present them as rules. Since this method is often used in market basket analysis to find which products are bought with what other products, it can also be used to find associated crimes conducted with what other crimes. Here, the rules are mainly evaluated by the two probability measures, support and confidence (Agrawal, Imielinkski & Swami, 1993; Yi et al., 2015). Association rule mining can also be used to identify the environmental factors that affect crimes using the geographical references (Koperski & Han, 1995). Incident association mining and entity association mining are two applications of association rule mining. Incident association mining can be used to find the crimes committed by the same offender and then the unresolved crimes can be linked to find the offender who committed them. Therefore, this technique is normally used to solve serial crimes like serial sexual offenses and serial homicides (Chen, 2006).

Similarity-based association mining and outlier-based association mining are two approaches used in incident association mining. Similarity-based association mining is used mainly to compare the features of a crime with the criminal's behavioral patterns which are referred as modus operandi or behavioral signature. In outlier-based association mining, crime associations will be created on the fact that both the crime and the criminal have the possibility of having some distinctive feature or a deviant behavior (Lin & Brown, 2006). Entity association mining/link analysis is the task of finding and charting associations between crime entities such as persons, weapons, and organizations. The purpose of this technique is to find out how crime entities that appear to be unrelated at the surface, are actually linked to each other (Chen, 2006). Link analysis is also used as one of the most applicable methods in social network analysis (Berry & Linoff, 2011) in finding crime groups, gate keepers and leaders (Chen et al., 2003).

Attribution can be used to link crimes to offenders. If two offences in different places involve the same specific type, those may be readily attributed to the same offender (Oatley & Ewwart, 2011).There are three types of link analysis approaches, namely Heuristic-based, Statistical-based and Template-based (Chen, 2006). Sequential pattern mining is also a similar technique to association rule mining. This method discovers frequently occurring items from a set of transactions occurred at different times (Chen et al., 2014). Deviation detection detects data that deviates significantly from the rest of the data which is analyzed. This is also called outlier detection, and is used in fraud detection (Chen et al., 2014; Capozzoli, Lauro & Khan, 2015).

In classification, the data points will be assigned to a set of predefined classes of data by identifying a set of common properties among them. This technique is often used to predict crime trends. Classification needs a reasonably complete set of training and testing data since a high degree of missing data would limit the prediction accuracy (Chen et al., 2014). Classification comes under supervised learning method (Chen, 2006; Chikersal, Poria & Cambria, 2015) which includes methods such as Bayesian models, decision trees, artificial neural networks (Chen, 1995) and support vector machines. String comparison techniques are used to detect the similarity between the records. Classification algorithms compare the database record pairs and determine the similarity among them. This concept can be used to avoid deceptive offender profiles. Information of offenders such as name, address, etc. might be deceptive and therefore the crime database might contain multiple records of the same offender. This makes the process of identification of their true identity difficult (Chen et al., 2014).

Systems and Methods

This section provides a description about the systems and methods used in developing the fuzzy based binary feature profiling for modus operandi analysis. First, an overview about how SL-CIDSS captures the logics of modus operandi is explained. Then a detailed description about the steps of the newly proposed algorithm is explained.

Figure 2 shows how SL-CIDSS database captures the crime types and subtypes. A crime record has a crime record flow. Typically, a crime is committed by a criminal and a particular accused might commit one or more crimes. A CRIME RECORD can be of one the 26 crime types. A particular CRIME RECORD will be considered under one main CRIME TYPE with the highest precedence in the order of seriousness. For example, a crime incident that includes a murder and a robbery will be categorized as a murder though a robbery has also taken place. But in the nature of crime section, all crimes followed by the main type will be stated. Therefore, the CRIME RECORD FLOW captures all the steps of the crime as a sequence of steps recorded. The crime flows that have been previously registered are mapped under CRIME FLOW CODE. Also, a particular CRIME RECORD instance can contain multiple SUB TYPES which are recorded as CRIME SUB TYPE. The SPECIAL CATEGORY captures the crimes with special features such as crimes occurring at the same location or retail shop. A crime may involve several special categories which are saved in the CRIME SPECIAL CATEGORY. The ACCUSED entity records the information of suspects and accused and they are related to crime through the CRIME SUSPECT entity.

As the first step of the newly employed method, a feature matrix is generated, resulting in a binary matrix representing the crime flows. This binary feature matrix is composed of the binary patterns generated on previous convictions of a particular criminal/suspect. This binary form of the feature matrix provides a provision to direct application of computer algorithms with methods such as Apriori based association rule mining. The reduced complexity of the binary feature matrices provides an easy manipulation over the categorical and continuous valued features. Figure 3 shows the steps of the proposed MO analysis algorithm.

Generating the feature matrix

Table 1 shows how the feature vectors are generated and provides the way to generate modi operandi of criminals as binary sequences. According to the table, events of the crime scene are observed starting from its crime type. After a particular crime type is identified, the feature vectors are updated with ones for each subtype and flow code that is available in the crime or suspect's modus operandi. The vectors will be filled by zeros in places which the modus operandi does not have any contact with. The column names to the feature matrix are generated in such a way that it covers the collection of main types, sub types, crime flows and special categories at hand. For example, if we consider the list of crime types, subtypes, crime flows and the special category in Table 1, it results in 21-bit feature vectors as shown in the last two columns.

In this manner we can produce binary MO patterns based on the crimes committed by different criminals as shown in the last two columns of Table 1. According to Table 1, Suspect 1 has committed a robbery with the subtypes, ABD/S003 (an abduction of a child from the legal guardian), ROB/S001 (an organized vehicle robbery) and the flows, ROB/F001 (Identity cards have been shown), ROB/F003 (accused has been wearing uniforms). Suspect 2 has committed a house breaking with the sub type BGL/S004 (use of stealth), and the flows, BGL/F001 (Entering from the window), BGL/F003 (Removing Grills).

Table 2 shows a feature matrix of binary patterns which is generated by considering the previous convictions of suspect 1 assuming that he has conducted another robbery (conviction 2). ct, st, fl and sc in Table 2 represent the abbreviations for ``crime type,'' ``sub type,'' ``crime flow'' and ``special category'' respectively.

Generating the dynamic MOs (DMOs) of the criminals

Dynamic MO is a binary feature vector which is generated on bit patterns of the feature matrix of a particular criminal. The main purpose of the DMO is to obtain a criminal specific crime flow which captures the crime patterns which are frequently followed by a particular criminal. It is named as the dynamic modus operandi as it is subject to change when the new crime flows are added to the feature matrix. Therefore, this addresses the changing nature of the patterns used by the criminals in committing crimes. First, a frequency threshold is generated using characteristic features of the feature matrix at hand which is the matrix of all crimes committed by the same criminal under consideration. The matrix shown in Table 3 is an example to a situation of a feature matrix generated on the previous convictions of a criminal. For the sake of simplicity, let's consider a feature matrix of 10 columns.

If we consider A--J of Table 3 as crime flow features of the corresponding MOs, we can understand that in the first MO the criminal has followed a crime flow of A-E-F-G-I. The same criminal has followed a crime flow of A-D-F-G-I in his second crime. Likewise the other two crime flows are, A-E-F-H-I and A-D-F-G-H-I respectively.

The DMO of a particular criminal is generated using the Apriori method (Adamo, 2001). Apriori method is used to find the crime entities with the frequency threshold (frt) which is generated according to Eq. (2). A demonstration of the generation of D in Eq. (1) on the properties of feature matrix is shown in Table 4. (1)(2)where, D = vector of distinct column frequencies of the feature matrix. yi = cells in each column, MD = Median of D, n = ∑f = number of values or total frequencies, c = cumulative frequency of the median class, h = class interval size.

The column-wise addition of the matrix shown in Table 4 gives 4, 0, 0, 2, 2, 4, 3, 2, 4 and 0. The distinct numbers are selected from the resulting vector which results in D = [0, 2, 3, 4]. The median of D is then divided by the number of instances (rows) in the matrix as the frt, which is 2.5/4 = 0.625 for the above case. Therefore, frt will range from 0 to 1. This value provides an insight to a fair threshold value for the Apriori method to generate the dynamic modus operandi with the most frequent elements. frt is used as the frequency threshold in finding the lengthiest MO with a probability of 0.625 because this value suggests that there is a moderate possibility of one feature having 0.625 probability in each of MO. This results in a dynamic modus operandi (DMO) as shown in Eq. (4), because the only transaction of crime attributes which provides a support of 0.625 is σ(A, F, G, I) as shown in Eq. (3). (3)(4)

Generating the complete MO profile (CMOP) of the criminals

The complete MO profile (CMOP) is obtained by the OR operation between the bits of each column of the feature matrix of the corresponding criminal. CMOP guarantees the provision of a composite crime flow by considering all of the previous crime flow entities of a particular criminal. For example, the complete profile for the feature matrix shown in Table 3 is obtained as shown in Table 5.

Therefore, . CMOP contains 1s for each place for which a particular crime flow entity has taken place at least once.

Finding the deviation probability (DP) of CMOP from the crime MO under consideration (UMO)

First, the deviation of CMOP and UMO is obtained according to Eq. (5). As the binary feature vectors are commonly used to represent patterns, many methods have been invented to find their similarity and distance (Cha, Tappert & Choi, 2010


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