1710, "from cause to effect," a Latin term in logic from c. 1300, in reference to reasoning from antecedent to consequent, based on causes and first principles, literally "from what comes first," from priori, ablative of prior "first" (see prior (adj.)). Opposed to a posteriori. Since c. 1840, based on Kant, used more loosely for "cognitions which, though they may come to us in experience, have their origin in the nature of the mind, and are independent of experience" [Century Dictionary]. Related: Apriorist; apriorism; aprioristic. The a is the usual form of Latin ab "off, of, away from" before consonants (see ab-).

"woman having charge of a religious house" (next in rank to an abbess), c. 1300, from Old French prioresse and directly from Medieval Latin priorissa, from prior "head of a priory of men" (see prior (n.)).

late 14c., prioritie, "state of being earlier (than something else), prior occurrence or existence," from Old French priorite (14c.) and directly from Medieval Latin prioritatem (nominative prioritas) "fact or condition of being prior" (source also of Spanish prioridad), from Latin prior (see prior (adj.)).

From c. 1400 as "precedence in right, place, or rank." In 1897 Century Dictionary wrote "Priority is the state or fact of coming first in order of time; what little use it has beyond this meaning is only a figurative extension," but in 20c. the sense shifted toward "fact or condition of coming first in importance or requiring immediate attention; thing regarded as more important than another or others." Wycliffe (early 15c.) renders prioritas into (Middle) English as furtherhead.

"religious house under the governance of a prior," next in dignity below an abbey, late 13c., priorie, from Anglo-French priorie (mid-13c.), from Medieval Latin prioria "monastery governed by a prior; office of a prior," from Latin prior (see prior (n.)). Middle English had priorwike for "position or office of a prior" (early 13c.); priority (early 15c.) also was used in this sense, as were priorhede (early 15c.), priorate (c. 1400).

"that which takes precedence, that which necessarily goes before," noun use of Latin neuter of prior (adj.) "former, earlier" (see prior (adj.)). The hybrid car (with a capital P- ) debuted in 1997 in Japan, 2001 in U.S. and Europe. The name supposedly was chosen because the car was regarded as a predecessor of new types. The classically proper plural of the car name is said to be Priora, but that is for the adjective.

Proto-Indo-European root forming prepositions, etc., meaning "forward," and, by extension, "in front of, before, first, chief, toward, near, against," etc.

It forms all or part of: afford; approach; appropriate; approve; approximate; barbican; before; deprive; expropriate; far; first; for; for-; fore; fore-; forefather; foremost; former (adj.); forth; frame; frau; fret; Freya; fro; froward; from; furnish; furniture; further; galore; hysteron-proteron; impervious; improbity; impromptu; improve; palfrey; par (prep.); para- (1) "alongside, beyond; altered; contrary; irregular, abnormal;" paradise; pardon; paramount; paramour; parvenu; pellucid; per; per-; percent; percussion; perennial; perestroika; perfect; perfidy; perform; perfume; perfunctory; perhaps; peri-; perish; perjury; permanent; permeate; permit; pernicious; perpendicular; perpetual; perplex; persecute; persevere; perspective; perspire; persuasion; pertain; peruse; pervade; pervert; pierce; portray; postprandial; prae-; Prakrit; pre-; premier; presbyter; Presbyterian; preterite; pride; priest; primal; primary; primate; primavera; prime; primeval; primitive; primo; primogenitor; primogeniture; primordial; primus; prince; principal; principle; prior; pristine; private; privilege; privy; pro (n.2) "a consideration or argument in favor;" pro-; probably; probe; probity; problem; proceed; proclaim; prodigal; produce; profane; profess; profile; profit; profound; profuse; project; promise; prompt; prone; proof; proper; property; propinquity; prophet; prose; prostate; prosthesis; protagonist; Protean; protect; protein; Proterozoic; protest; proto-; protocol; proton; protoplasm; Protozoa; proud; prove; proverb; provide; provoke; prow; prowess; proximate; Purana; purchase; purdah; reciprocal; rapprochement; reproach; reprove; veneer.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pari "around, about, through," parah "farther, remote, ulterior," pura "formerly, before," pra- "before, forward, forth;" Avestan pairi- "around," paro "before;" Hittite para "outside of," Greek peri "around, about, near, beyond," pera "across, beyond," paros "before," para "from beside, beyond," pro "before;" Latin pro "before, for, on behalf of, instead of," porro "forward," prae "before," per "through;" Old Church Slavonic pra-dedu "great-grandfather;" Russian pere- "through;" Lithuanian per "through;" Old Irish ire "farther," roar "enough;" Gothic faura "before," Old English fore (prep.) "before, in front of," (adv.) "before, previously," fram "forward, from," feor "to a great distance, long ago;" German vor "before, in front of;" Old Irish air- Gothic fair-, German ver-, Old English fer-, intensive prefixes.