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Latin 101: (Almost) every phrase you need to know to get by in English


George Edward Robertson - Public Domain

John Burger - published on 10/21/19

Our language is liberally sprinkled with Latin phrases. Do we know what they mean, and are we using them correctly?

The Latin language has had an outsized influence on languages all over the world. It’s no wonder, since the Romans, in their empire building, left it all over the Mediterranean world. And many explorers to the New World and the Indies were people who spoke Latinate languages—Spanish, Portuguese and French.

Not to mention the influence of the Latin (Roman) Catholic Church.

Today, it’s almost impossible to speak for a few minutes without including some Latin-based word or expression. And many terms in law, medicine, philosophy and other disciplines are straight out of the language of the Romans.

Here’s a modest guide to some of the major Latin words and expressions, with special attention to those that are sometimes most misunderstood or misused by modern American speakers.

A contrario

Equivalent to “on the contrary” and “au contraire.” An argumentum a contrario (“argument from the contrary”) is an argument or proof by contrast or direct opposite.

Ad absurdum

In logic, to the point of being silly or nonsensical. Not to be confused with ab absurdo (“from the absurd”).

Ad astra per aspera

“To the stars through difficulties.”

Ad hoc

Generally means “for this,” in the sense of improvised or intended only for a specific, immediate purpose. It’s usually used to refer to an ad hoc committee.

Ad hominem

“At the man.” An argumentum ad hominem is a logical fallacy consisting of criticizing a person when the subject of debate is the person’s ideas or argument, on the mistaken assumption that the soundness of an argument is dependent on the qualities of the proponent.

Ad infinitum

Enduring forever. Used to designate a property that repeats in all cases in mathematical proof. Also used in philosophical contexts to mean “repeating in all cases.”

Ad lib

Comes from the phrase ad libitum, meaning “toward pleasure,” “according to what pleases” or “as you wish.” Libitum comes from the past participle of libere, “to please.” In music, for example, someone “ad libbing” is improvising.

Ad litem

Literally, “to the lawsuit,” this legal phrase refers to a party appointed by a court to act in a lawsuit on behalf of another party who is deemed incapable of representing himself. An individual who acts in this capacity is called a guardian ad litem.

Ad majorem Dei gloriam

“For the greater glory of God,” the motto of the Society of Jesus, often abbreviated AMDG.

Ad multos annos

“To many years.” A wish for a long life; similar to “many happy returns.”

Ad nauseam

“To the point of disgust.” This phrase sometimes is used as a humorous alternative to ad infinitum. An argumentum ad nauseam is a logical fallacy whose erroneous proof is proffered by prolonged repetition of the argument, i. e., the argument is repeated so many times that persons are “sick of it.”


An item to be added, especially as a supplement to a book. The plural is addenda.

Alma mater

Literally “nourishing mother,” this term is used for the university one attends or has attended.

Amicus curiae

A “friend of the court,” an adviser, or a person who can obtain or grant access to the favor of a powerful group, e. g., the a Roman Curia. In current U.S. legal usage, an amicus curiae is a third party allowed to submit a legal opinion in the form of an amicus brief to the court.

Anno Domini

“In the year of the Lord.” The initials always come before the year, e.g., “Augustus died in AD 14.”

A posteriori

“From the latter.” Based on observation, i. e., empirical evidence; the reverse of a priori. Used in mathematics and logic to denote something that is known after a proof has been carried out. In philosophy, used to denote something known from experience.

A priori

“From the former.” Presupposed independent of experience; the reverse of a posteriori. Used in mathematics and logic to denote something that is known or postulated before a proof has been carried out. In philosophy, used to denote something is supposed without empirical evidence. In everyday speech, it denotes something occurring or being known before the event.

Ars gratia artis

“Art for art’s sake.” If you’re the kind of person who likes to watch a movie from the absolute beginning to the very end, you may have noticed this motto on the MGM logo, when the lion roars. Wikipedia, however, says that the better word order in Latin is Ars artis gratia.

Bona fide

“In good faith.” In other words, “well-intentioned.” In modern contexts, this often has connotations of “genuinely” or “sincerely.”

Carpe diem

“Seize the day.” Take advantage of the present moment.


“Around,” “approximately” or “about,” usually used of a date.

Compos mentis

“In control of the mind.” Describes someone of sound mind. A legal principle, non compos mentis (not in control of one’s faculties), is used to describe an insane person.


“Compare.” The abbreviation cf. is used in a text to suggest a comparison with something else.

Cor ad cor loquitur

“Heart speaks to heart.” From St. Augustine’s Confessions, referring to a prescribed method of prayer: having a “heart to heart” with God. The phrase is commonly used in reference to a later quote by recently canonized John Henry Newman.


Things to be corrected.

Cum laude

“With praise.” Some people graduate from college, while others graduate cum laude. If your grades have been really good, you’ll graduate magna cum laude (“with great praise”) or summa cum laude (“with the greatest praise”).

Curriculum vitae

… and if you’ve just graduated, you’re more likely to have just a résumé. But with more experience, you can put together your CV. The Latin means literally “course of life.” It’s an overview of a person’s life and qualifications.

De facto

“By deed.” Said of something that is the actual state of affairs, in contrast to something’s legal or official standing, which is described as de jure. De facto refers to “the way things really are” rather than what is officially presented as the fact of the matter in question.

De gustibus non est disputandum

“In matters of taste, there can be no disputes.” One person likes Coke, another likes Pepsi. They’re both right.

De jure

“By law.” Official, in contrast with de facto; analogous to “in principle,” whereas de facto is “in practice.” In other contexts, it can mean “according to law,” “by right,” and “legally.”

Deo gratias

“Thanks be to God.”

Deo volente

“God willing.”

Deus ex machina

“A god from a machine.” A contrived or artificial solution, usually to a literary plot. (From a classical Greek theatrical device, in which a play’s loose ends were resolved by the appearance of an actor portraying a god using a mechanical contraption to rise out of the earth or descend from the sky.)

Dominus vobiscum

“The Lord be with you.” A phrase used in the Latin Catholic liturgy. The response is Et cum spiritu tuo—“And with your spirit.”

Dramatis personae

The cast of characters of a dramatic work.

E pluribus unum

Literally, “out of more (than one), one.” The former national motto of the United States, which “In God We Trust” later replaced; therefore, it is still inscribed on many U.S. coins and on the United States Capitol.


“Veteran.” Retired from office. Often used to denote an office held at the time of one’s retirement, as an honorary title, e.g. professor emeritus.


“Therefore.” Denotes a logical conclusion (e.g. cogito ergo sum, Descartes’ theory, “I think, therefore I am”).


“Error.” Lists of errors in a previous edition of a book are often marked with the plural errata (“errors”).

Et al.

Common abbreviation for et alii, which is used similarly to et cetera (“and the rest”) to denote names that, usually for the sake of space, are unenumerated/omitted.

Ex cathedra

“From the chair.” Cathedrals are so named not because they are the largest church but because they are the churches containing the cathedra, the bishop’s chair from which he rules and teaches. The phrase ex cathedra is applied in particular to teaching from the Bishop of Rome, i.e., the instruction that the pope gives that is to be held by all the faithful.

Ex post facto

“From a thing done afterward.” Said of a law with retroactive effect.

Exempli gratia (e.g.)

“For the sake of example, for example.”


“They leave.” Often seen at the end of a scene in a play. Also, in exeunt omnes, “all leave.”

Extra omnes

You’ll only need to know this if you ever happen to be in the room where a papal conclave is about to take place. It is the command given by the Master of the Papal Liturgical Celebrations before the secret session to elect a new pope begins, meaning “Anyone who doesn’t belong here should get out.”

Habeas corpus

“You should have the body.” A legal term commonly used as the general term for a prisoner’s legal right to challenge the legality of their detention.

Habemus papam

“We have a pope.” The words used to announce the election of a new Bishop of Rome.

Hic jacet

“Here lies.” You often find this phrase on very old tombstones in cemeteries, followed by the name of the deceased.

Honoris causa

“For the sake of honor.” Said of an honorary title, such as “Doctor of Science honoris causa.”

ibidem (ibid.)

“In the same place.” Usually used in bibliographic citations to refer to the last source previously referenced.

id est (i.e.)

“That is,” “that means,” “in other words,” “namely,” or sometimes “in this case,” depending on the context.


“Let it be printed.” An authorization to publish, granted by some censoring authority, such as a bishop.

In absentia

“In the absence.” Used in a number of situations, such as in a trial carried out in the absence of the accused.

In loco parentis

“In the place of a parent.” Assuming parental or custodial responsibility and authority (e.g., schoolteachers over students); a legal term.

In medias res

“In the middle of things.” Refers to the literary technique of beginning a narrative in the middle of, or at a late point in, the story, after much action has already taken place.

In pectore

“In the heart.” A cardinal named in secret by the pope.

In re

“In the matter of.” A legal term used to indicate that a judicial proceeding may not have formally designated adverse parties or is otherwise uncontested. The term is commonly used in case citations of probate proceedings.

In utero

“In the womb.”

In vino veritas

“In wine there is truth.” One tends to speak more freely over a good Bordeaux, for example.

In vitro

“In the glass.” An experimental or process methodology performed in a “non-natural” setting (e.g. in a laboratory using a test tube or Petri dish), and thus outside of a living organism or cell.

In vivo

“In life, in a living thing.” An experiment or process performed on a living specimen.

Inter alia

“Among other things.” A term used in formal extract minutes to indicate that the minute quoted has been taken from a fuller record of other matters, or when alluding to the parent group after quoting a particular example.

Ipso facto

“By the fact itself.” By that very fact.

Magnum opus

“Great work.” A person’s masterpiece.

Mea culpa

“My fault.” In the Confiteor, a prayer in the Latin Catholic Mass, the faithful admit that their sins are their own responsibility. “Through my fault, through my fault, through my most grievous fault (mea maxima culpa).”

Motu proprio

“On his own initiative,” or “by his own accord.” Identifies a class of papal documents, administrative papal bulls.

Mutatis mutandis

“After changing what needed to be changed.” With the appropriate changes.

Nihil obstat

“Nothing prevents.” A notation, usually on a title page, indicating that a religious authority has reviewed a book and found nothing objectionable to faith or morals in its content.

Non sequitur

“It does not follow.” In general, a comment which is absurd due to not making sense in its context (rather than due to being inherently nonsensical or internally inconsistent), often used in humor. As a logical fallacy, a conclusion that does not follow from a premise.

Nota bene (N.B.)

“Mark well.”

Opera citato (op. cit.)

“In the work that was cited,” used in academic works when referring again to the last source mentioned or used.

Ora et labora

“Pray and work.” This principle of the Benedictine monasteries reads in full: “Ora et labora (et lege), Deus adest sine mora.” “Pray and work (and read), God is there without delay” (or to keep the rhyme: “Work and pray, and God is there without delay.”

Ora pro nobis

“Pray for us.”

Oremus pro invicem

“Let us pray for each other.”


“With all due respect to,” “with due deference to,” “no offense to,” or “despite (with respect).” Used to politely acknowledge someone with whom the speaker or writer disagrees or finds irrelevant to the main argument.


“Here and there, everywhere.” Less literally, “throughout” or “frequently.” Said of a word, fact or notion that occurs several times in a cited text. Also used in proofreading, where it refers to a change that is to be repeated everywhere needed.

Pax et bonum

“Peace and good.” A greeting often associated with the Franciscans.

Per diem

“By day,” or “per day.” A specific amount of money an organization allows an individual to spend per day, typically for travel expenses.

Per se

“Through itself.” Also “by itself” or “in itself.” Without referring to anything else, intrinsically, taken without qualifications, etc. A common example is negligence per se.

Persona non grata

“Person not pleasing.” An unwelcome, unwanted or undesirable person. In diplomatic contexts, a person rejected by the host government.


“It pleases.” An expression of assent.

Posse comitatus

“Force of the county.” To be able to be made into part of a retinue or force. In common law, a sheriff’s right to compel people to assist law enforcement in unusual situations. In federal law, the act that prohibits US troops from being used as law enforcement on US soil unless authorized by the Constitution or a specific act of Congress.

Post hoc ergo propter hoc

“After this, therefore because of this.” A logical fallacy where one assumes that one thing happening after another thing means that the first thing caused the second.

Post meridiem (P.M.)

“After midday.” The period between noon and midnight. The Latin for morning is ante meridiem (A.M.)

Prima facie

“At first sight.” Used to designate evidence in a trial which is suggestive, but not conclusive, of something (e.g., a person’s guilt).

Pro se

“For oneself.” To defend oneself in court without counsel.

Quid pro quo

“This for that.” Signifies a favor exchanged for a favor.

Quo vadis?

“Where are you going?” According to the Vulgate translation of John 13:36, St. Peter asked Jesus Domine, quo vadis? (“Lord, where are you going?”).

Quod erat demonstrandum (Q.E.D.)

“What was to be demonstrated.” The abbreviation is often written at the bottom of a mathematical proof.

Requiescat in pace (R.I.P.)

“Let him/her rest in peace,” or “may he/she rest in peace.” It’s convenient that “RIP” corresponds with the English “Rest In Peace.”

Sede vacante

“With the seat being vacant.” This refers to the absence of the ruling bishop of a diocese, in particular, when a pope dies or resigns. Until a new Bishop of Rome is elected (or the pope appoints a new bishop to a diocese), the period of sede vacante is known as the interregnum.

Semper fidelis

“Always faithful.” The motto of the U.S. Marine Corps.


“Thus.” This simple word states that the preceding quoted material appears exactly that way in the source, despite any errors of spelling, grammar, usage, or fact that may be present.

Stare decisis

“To stand by the decided things.” To uphold previous rulings, recognize precedent.

Sui iuris

“Of one’s own right.” Capable of responsibility. Has both legal and ecclesiastical use. There are several sui iuris Eastern Catholic Churches that are in communion with Rome but self-governing.

Tabula rasa

“Scraped tablet,” or “blank slate.” Romans used to write on wax-covered wooden tablets, which were erased by scraping with the flat end of the stylus.

Tempus fugit

“Time flies.”

Terra firma

“Solid earth,” or ground.

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