| Ad absurdum | To absurdity |
| Ad astra | To the stars; to the utmost |
| Ad hoc | Formed for a specific purpose |
| Ad hominem | Personal, relating to an individual |
| Ad infinitum | Forever, endlessly |
| Ad majorem Dei gloriam | To the greater glory of God |
| Ad nauseam | Endlessly, to a disgusting or ridiculous degree |
| Ad valorem | According to the value (of goods) |
| A fortiori | All the more; said of a second conclusion that is even more logical than the first |
| Alea jacta est* | The die is cast |
| Alma mater | One’s university or college |
| Alter ego | One’s second self |
| Amicus curiae | Friend of the court |
| Anno domini | In the year of the Lord |
| Annus horribilis | Terrible year |
| Annus mirabilis | Wonderful year |
| Ante bellum | Before the war |
| A posteriori | Making conclusions based on fact rather than obvious principles |
| A priori | Making conclusions based on theory rather than fact |
| Aqua vitae | Literally “water of life,” designating brandy or other strong liquor |
| Argumentum ad hominem | Argument based on personal attacks rather than the person’s reasonings |
| Ars gratia artis. | Art for art’s sake |
| Ars longa, vita brevis | Art is long, life is short |
| Bona fide | In good faith; genuine |
| Bona fides | Documents proving identity or authority |
| Camera obscura | Camera with a dark chamber and an aperture that uses mirrors to project an image on to a screen |
| Carpe diem | Enjoy the day; take advantage while the opportunity is there |
| Casus belli | Grounds for fighting, especially a war |
| Caveat | Caution |
| Caveat empto | Let the buyer beware |
| Cogito ergo sum | I think, therefore I am (from Descartes) |
| Compos mentis | Of sound mind |
| Corpus delicti | Facts of the crime; body of the crime |
| Cui bono | To whose benefit; to what purpose |
| Cum grano salis | With a grain of salt |
| Cum laude | With honors |
| De facto | Existing by fact and not by choice |
| De gustibus non est disputandum | To each his own taste |
| Dei gratia. | By the grace of God |
| De jure | By right according to a legal system |
| Delirium tremens | Alcoholic withdrawal syndrome |
| Deo gratias | Thanks to God |
| Deo volente | God willing |
| De profundis | Arising from extreme despair or pain |
| E pluribus unum | Out of many, one; from many, one |
| Ergo | Therefore |
| Et al(alii) | And other things |
| Et cetera | And so forth |
| Ex cathedra | From a position of authority |
| Exempli gratia | For example |
| Ex libris | From the library of |
| Ex officio | By virtue of an office held |
| Ex post facto | After the fact; by reason of something having been done afterwards |
| Factotum | One who does everything; jack-of-all-trades |
| Gratis | Free |
| Habeas corpus | Writ requiring the appearance of prisoner in court to determine if he has been legally detained |
| Homo sapiens | Member of the human species |
| Horribile dictu | Terrible to relate |
| Id | Part of the psyche that is the source of psychic energy |
| Id est | That is (abbreviated i.e.) |
| Imprimatur | Official sanction to publish a text (especially from a bishop or pope) |
| In absentia | In the absence of the person concerned |
| In camera | In secret |
| In excelsis | In the highest |
| In extremis | In great danger, especially of dying |
| In flagrante delicto | In the act of committing a crime |
| Ignis fatuus | Evanescent phosphorescent light seen at night over a marshy area will-o’-the wisp; something misleading |
| In hoc signo vinces | In this sign thou will conquer |
| In loco parentis | In the place of the parent |
| In media res | In the middle of things, especially a plot or play |
| In memoriam | In memory of, especially in an obituary notice |
| In situ | In its original place |
| Inter alia | Among other things |
| In toto | As a whole, completely |
| In vino veritas | In wine, there is truth—that is, one speaks freely under the influence of drink |
| In vitro | In a test tube |
| Ipso facto | By the very fact itself |
| Lapsus linguae | Slip of the tongue |
| Libido | Sexual drive |
| Magna cum laude | With high honors |
| Magnum opu | (an artist’s, writer’s) Greatest work |
| Mare | Sea; especially those dark areas on the moon and Mars |
| Mea culpa | Admission of guilt |
| Memento mori | Any reminder of your mortality |
| Mens sana in corpore sano | Sound mind in a sound body |
| Mirabile dictu | Wonderful to relate |
| Modus operandi (MO) | Method of operation |
| Modus vivendi | Life style; temporary arrangement for two parties living together but at odds with one another |
| Mores | Morals or customs of a country or group |
| Mutatis mutandis | Allowing for the necessary changes |
| Ne plus ultra | Furthest point attainable; most perfect of anything |
| Nolle prosequi | (in law) Prosecutorial statement not to further pursue a suit |
| Nolo contendere | Defendant’s plea accepting conviction but without admitting guilt |
| Non compos mentis | Not of sound mind |
| Non sequitu | Conclusion that does not follow from the premise |
| Nota bene (NB | Take note of what follows |
| Obiter dictum | Passing remark; (in law) judge’s offhand remark |
| Omnia vincit amor | Love conquers all |
| Opus | Creative work, especially a musical composition |
| O tempora! O mores! | Oh the times! Oh the manners! (exclamation from Cicero suggesting displeasure with changing times, changing values) |
| Paterfamilias | Head of family |
| Pater patriae | Father of his country; founder of the nation |
| Pax | Peace |
| Pax Romana | Area over which Roman law and authority was sovereign |
| Pax vobiscum | Peace be with you |
| Pax vobiscum | Peace be with you |
| Peccavi | Admission of having been in the wrong |
| Per annum | Per year |
| Per capita | Per person |
| Per diem | Per day |
| Per se | By itself |
| Persona | Characters in a drama; (in psychology) outward personality as seen by others |
| Persona non grata | An unacceptable person |
| Post mortem (P.M.) | After death |
| Post scriptum (P.S.) | Literally “written after,” for an additional note to a letter |
| Prima facie | At first view; a prima facie case is one in which initial evidence is thought sufficient to justify further examination and prosecution |
| Primus inter pares | First among equals |
| Pro bono | For the public good |
| Pro et con | For and against (as an argument) |
| Pro forma | As a matter of formality or etiquette |
| Prosit! | To your health! |
| Pro tempore | For the time being |
| Quid pro quo | Something for something |
| Quod erat demonstrandum | Which was to be proved |
| Quod erat faciendum | Which was to be done |
| Quondam | Formerly |
| Quo vadis | Where are you going? |
| Rara avis | Something or someone rarely encountered |
| Re | With regard to |
| Reductio ad absurdum | Manner of disproving a premise by assuming a conclusion to be incorrect and going back to show that it was impossible |
| Requiescat in pace (RIP) | Rest in peace |
| Rigor mortis | Stiffness of a corpse developing within hours of death |
| Semper fidelis | Ever faithful |
| Sic transit gloria mundi | Thus passes the glory of the world |
| Sine qua non | Literally “without which nothing,” for something indispensable |
| Stare decisis | Policy of law that the court will abide by a previous decision |
| Status quo | Existing state of affairs |
| Sub rosa | In secret |
| Sui generis | Unique; in a class by itself |
| Tabula rasa | Clean slate |
| Tempus fugit | Time passes quickly |
| Terra firma | Solid ground |
| Terra incognita | Unexplored region, be it geographical, scientific, etc. |
| Ultima thule | Furthest point accessible; any distant place |
| Urbi et orbi | To the city, Rome, and to the world (used in a Papal blessing or pronouncement) |
| Vade mecum | Literally “go with me,” for a handbook or something used as a ready reference |
| Verbatim | Word for word |
| Veritas | Truth |
| Vice versa | The order being reversed |
| Vox populi | Voice of the people |
| Vox populi, vox dei | Voice of the people is the voice of God |