a priori from the prior The process of reasoning from what is known to what is unknown. Can also mean taking action hastily, without discussion.
ad hoc* for this purpose Something which is done ad hoc is put together quickly, or assembled for a limited purpose. For example, an ad hoc committee is assembled to address one problem and then dissolve itself.
ad hominem* to the man Ad hominem is arguing a position by attacking another person, rather than debating ideas. It is often used as "an ad hominem attack."
ad nauseam* to nausea When someone or something goes on and on until everyone is sick of it, it is done ad nauseam.
alma mater nourishing mother Usually this term is applied to the school or college one attended, though it can be applied to one's town, state, or country of birth.
alter ego* another I An alter ego is someone who is like another person, or like what another person would want to be. For example, Batman is Bruce Wayne's alter ego.
amicus curiae* friend of the court When a person or group is not a party to a lawsuit, but they file papers to try to convince the court to decide one way or the other, they file amicus curiae briefs. This is supposed to mean that they are just helping the court do its job.
anno Domini year of Our Lord Usually abbreviated A.D., refers to the number of years passed since the birth of Christ.
ante bellum* before the war Referring to any period of time before a war, but specifically applied to the condition of the American South before the Civil War.
ars gratia artis art for the sake of art This means art done only for the beauty of the art, without regard for the marketability of the art. It is also a trademark of Metro-Goldwyn-Mayer (MGM) studios.
bona fide* good faith Someone done with good intentions is done bona fide. Also used to mean true, as in a bona fide gold watch.
carpe diem seize the day Carpe diem means to live only for what the day brings, caring nothing for the future. Generally thought to be a bad thing, but also meaning that life should be savored and lived in the present.
caveat emptor buyer beware Usually used to make a young person aware that they must be careful when dealing with salespeople.
certiorari making certain The Supreme Court issues a writ of certiorari when it decides to accept a legal case, to literally "make certain" it was decided correctly.
circa* about Usually used as an approximation of time or date. For example, steamships came into use circa 1800.
cogito ergo sum I think therefore I am. A phrase used by Rene Descartes to imply that a being which thinks must actually exist, from his Discourse on Method.
cui bono? who benefited When tracing complicated schemes, one often asks "cui bono," meaning who ultimately benefitted from the scheme. When you find who benefits, you may find who is responsible.
curriculum vitae course of life A curriculum vitae is similar to, but more in-depth than, a resume. It basically spells out that the accomplishments and major themes of one's life.
de facto* from the fact Something which is de facto exists in fact but perhaps not in name. For example, an advisor to a king may be the real, or de facto, ruler of a country, but without the title.
de gustibus non disputandum est there is no arguing over tastes Since everyone has their own irrational likes and dislikes, there is no use arguing about it. For example, is vanilla or chocolate tastier? Well, de gustibus non disputandum est.
deo gratias Thanks be to God. Literally thanking God for something, but figuratively just happy about anything.
deus ex machina God out of the machine A deus ex machina ending is a contrived and highly unlikely ending. Or, it could be used to say that only a miracle, a deus ex machina, could save the day.
dramatis personae* persons of the drama Dramatis personae is usually a listing of characters in a play or movie, but can also refer to any list of people.
e pluribus unum out of many, one Motto of the United States, meaning that the Union was formed out of the many states but forms one country.
erratum error An erratum sheet is often printed as a supplement to a published work, showing that there are known errors.
et alii and others Used at the end of a list to signify others as well. Usually abbreviated, such as, "This work was produced by John, Jim, Susan, et. al."
et cetera* and so on A famous phrase of the King of Siam, meaning other things have been left out. Usually abbreviated etc.
ex cathedra from the chair When the Pope speaks authoritatively from the chair of Peter, he speaks ex cathedra. Applied by extension to any definitive statement of fact or policy.
ex libris from the books Means from the books or the library of a certain person. Usually followed by a name.
ex officio* from the office Usually used as in "ex officio member," meaning that someone is a member of a committee or group due to his office, not his other qualifications.
ex post facto* from after the fact Ex post facto is something that is done or said after the event happens. For example, the US Constitution forbids ex post facto laws, meaning prosecuting someone for an act committed before the law was passed.
fiat voluntas tua Thy (God's) will be done. Meant to signify that a person will not resist the will of another person, from the Our Father prayer.
habeas corpus* you should have the body A "writ of habeas corpus" is a court order to physically bring a prisoner in court to face charges. This is a protection against long-term or indeterminate imprisonment without charging someone with a crime.
ibidem the same place Used in scholarly citations to refer to a source already cited. Usually abbreviated as ibid.
id est that is Usually used as "in other words." Always abbreviated as i.e.
in camera* in the chamber A action done in camera is done secretly or without oversight.
in loco parentis in the place of parents Anyone who takes care of children or young people, and therefore shares in the authority of parents, is in loco parentis. This is usually said of schools or other temporary guardians of children.
in medias res in the middle of things Novels and television shows often start in medias res, and then use flashbacks to show how the events came to pass.
in memoriam in memory Something done to honor the memory of a deceased person, especially a lasting tribute, is done in memoriam.
in saecula saeculorum in ages of ages Used to signify forever.
in vino veritas in wine there is truth Means that when people speak in an unguarded manner, such as when drinking, they often speak the truth.
in vitro in glass Used in the phrase "in vitro fertilization" to denote fertilization of an egg taking place in a test tube.
inter alia among other things Used to signify that one is talking about one of a number of things. For example, "I don't like dogs inter alia because they bite," meaning that there are other reasons as well.
ipso facto* by the fact itself Generally means "therefore." The phrase is used to show that one thing absolutely proves another thing.
magna cum laude* with great praise The second highest recognition of scholarship in high school or college (highest is "summa cum laude").
magnum opus* great work An author or artist's greatest, most impressive work is his magnum opus. By extension, any great or difficult labor undertaken could be a magnum opus.
mea culpa my fault A mea culpa is a offered up as a total acceptance of guilt.
memento mori* remember to die A memento mori is a reminder that all living things will die eventually and that all glory and honor is passing. A memento mori was historically a skull kept upon ones desk.
modus operandi mode of working A modus operandi is the way that someone or something habitually works. Often in police shows, it is abbreviated as MO.
ne plus ultra no more beyond Something that is the greatest possible is the ne plus ultra of its class.
nolo contendere I do not contend. A legal plea of a defendant in which one does not deny the validity of the charge, but does not admit to culpability either.
non compos mentis* not sound mentally Anyone of mental impairment can be said to be non compos mentis.
non sequitur* it does not follow A logical fallacy in which a line of reasoning does not hold together, because one thing does not logically follow another.
nota bene note well Used to call attention to a particularly important point. Usually abbreviated N.B.
novus ordo seclorum new order of ages Motto from the Great Seal of the United States. It is to indicate that the United States was seen as a new type of nation in history.
ora et labora pray and work The motto of monks in the Middle Ages, who prayed for what they needed, but also worked for it.
ora pro nobis pray for us Anytime one would like others to pray for them, they might say "ora pro nobis."
passim throughout A scholarly citation in which an entire work or a large part of the work is cited, rather than a particular passage. For example, "Sections 4 and 5, passim."
paterfamilias father of the family The head of an extended family is called the paterfamilias. Can be used by extension to refer to any revered person who has inspired a company, association, or movement.
per annum* by year The phrase refers to the amount of money that someone will be paid per year.
per capita* by head A way of counting based upon the number of people, for example per capita income is the total income divided by the number of people.
per se* of itself A phrase denoting the very essence of a thing. For example, murder is evil per se, regardless of motivation.
posse comitatus power of the county Posse comitatus is often shortened to just posse, especially in Old West usage. Any group of citizens banding together could be called a posse comitatus.
post hoc propter hoc* after this because of this When someone says this, they mean that since one thing happened after another thing, the first thing caused the second. This is usually presented as a logical fallacy, meaning that the first thing did not really cause the second.
post mortem* after death A post mortem examination is often done to determine a cause of death. The phrase can be used by extension to denote looking at the causes of the demise of any activity, such as a corporation that goes bankrupt.
prima facie* at first view Prima facie conclusions are based only upon first looks and not deep investigation. Often used in "prima facie evidence" meaning that something is considered evidence until proven otherwise.
pro bono for good When lawyers or doctors do work "pro bono" they do it for free, or just "for the good" that it does. This can also be applied to any charitable work.
pro forma for form A pro forma action is something that is done merely as a formality, because a rule requires it, or for appearance sake. For example, an employee might make a pro forma request for a raise each year, knowing he won't get it.
quid pro quo something for something In a bargain, both sides must get something fair, a quid pro quo. This term is also used in politics, to denote the explicit selling of favors or offices.
quo vadis where are you going A Biblical phrase (from the Vulgate). By extension, anytime we wonder in what direction a person or organization is heading, we may ask "Quo vadis?"
quod erat demonstrandum which was to be demonstrated Always abbreviated Q.E.D., it is meant to show that a solution has been fully provided, or an argument has been fully demonstrated.
reductio ad absurdum reduced to absurdity A technique in logic in which a person's thesis is taken to its final conclusion and shown to be illogical. For example, if we say that killing any living thing is murder, then we could not even treat people for bacterial infections, which is absurd.
requiescat in pace rest in peace The traditional blessing on the dead, but by extension can be said of any final ending. Often abbreviated R.I.P.
saturnalia* Saturnalia The Saturnalia was a knock-down, drag-out festival in ancient Rome, in which just about anything was okay. By extension, it refers to any type of debauchery, especially drunken revelry.
semper fidelis always faithful Motto of the U.S. Marine Corps, but by extension can be applied to any faithful person or thing.
sic thus Used often in quotations to show that an error was contained in an original quote. It is often used to draw attention to the lack of learning of a person.
sic semper tyrannis thus always to tyrants The motto of Virginia, meaning that patriots will always rise up against tyrants. Perhaps said by John Wilkes Booth after killing Abraham Lincoln.
sine qua non without which not A sine qua non is a cause which must exist for an effect to exist. For example, adequate funding is a sine qua non of building a house.
sub poena* under punishment A legal document requiring a person to appear in court or before Congress, under pain of fine or imprisonment.
sub rosa under the rose Possibly deriving from Roman mythology, sub rosa is anything done secretly or covertly, as in a sub rosa operation.
sui generis its own kind Something which is sui generis is one of a kind. This could be applied, for example, to Michael Jordan.
tabula rasa blank tablet Figuratively, a tabula rasa is any person who is unlearned, and hence can be taught.
tempus fugit* time flies A commentary on how quickly the days pass in a life, or the fact that one is late.
terra firma* solid earth This phrase indicates the land as oppsed to the sea. Someone who is seasick might well long to stand on terra firma.
una voce with one voice This phrase indicates that something was done unanimously, as with one voice.
urbi et orbi the city and the world This is the traditional blessing given by the Pope, but by extension it can mean anything universal.
veni, vidi, vici I came, I saw, I conquered. Said by Julius Caesar after a victory over the king of Pontus. By extension, it could be said by anyone who has quickly and completely vanquished an enemy or completed a difficult task.
veritas truth Motto of Harvard, and used to emphasize that something is true.
vice versa* the change turning A phrase used to show that something is true in two ways. For example, "I don't like my neighbor, and vice versa," means my neighbor doesn't like me either.
vox populi, vox Dei voice of the people, voice of God Means that what the people want is to be regarded as the highest good, as if God himself said it.
