a prior
from what is already known (reasoning 'a priori' is a logical process in which consequences are deduced from principles that are assumed).
ab initio
from the beginning
ad astra per aspera
to the stars through difficulties (Motto of Kansas)
ad hoc
for this purpose (an 'ad hoc' committee is a temporary committee established to accomplish a particular task)
ad hominem
against the man (arguing personally instead of logically)
ad infinitum
without limit, forever
ad nauseam
to the point of (causing) nausea; endlessly (anything unpleasant that appears to go on endlessly may be said to be proceeding 'ad nauseam')
agnus Dei
lamb of God
alea iacta est
the die is cast (upon crossing the Rubicon in 49 B.C., Julius Caesar made this statement meaning that he had made a bold and irretrievable decision)
amor omnia vincit
Love conquers all (famous line of Vergil's; Vergil goes on to say 'et nos cedamus amori'- And let us yield to love)
ars gratia artis
art for the sake of art (Motto of Metro-Goldwyn-Mayer, motion picture producers)
ars longa, vita brevis
art is long, life is short (coined by Hippocrates)
ars poetica
the art of poetry (quote from Horace)
bis vivit qui bene vivit
he lives twice who lives well (John Milton "Paradise Lost")
caveat emptor
let the buyer beware (rule of law warning potential purchasers of goods that they are not protected from failure of the seller to live up to the bargain except to the extent that the sales contract stipulates)
cogito ergo sum
I think, therefore, I am (famous philosophical Rene Descartes - "Discourse on Method")
compos mentis
of sound mind ("in full possession of mental powers")
corpus delicti
the terrible evidence that a crime has been committed; literally "body of the crime" (fact or set of facts needed to establish a crime has been committed)
cum grano salis
with a grain of salt; take lightly (implies a certain caution or reserve)
de facto
in reality (differentiates that which exists in fact (de facto) from that which exists legally (de iure) de facto rulers, in contrast to de iure rulers, are calling the signals)
delenda est Carthago
Carthage must be destroyed (Cato the Elder repeatedly egged the Roman Senate on to destroy Carthage with this ominous phrase)
de mortius nihil nisi bonum
speak kindly of the dead (Chilon of Spart, 6th century BC - Latin translation)
de profundis
out of the depths (of despair) Psalm 130; quoted by Oscar Wilde in 1895 after he had been imprisoned
deus ex machina
an unlikely and providential intervention (has its origins in the Greek theatre)
dis aliter visum
man proposes, God disposes (Vergil, in the Aeneid - literally translated "it seemed otherwise to the gods")