prone (adj.)
c. 1400, "naturally inclined to something, apt, liable," from Latin pronus "bent forward, leaning forward, bent over," figuratively "inclined to, disposed," perhaps from adverbial form of pro "before, for, instead of" (see pro-) + ending as in infernus, externus. Meaning "lying face-down" is first recorded 1570s. Literal and figurative senses both were in Latin; figurative is older in English. Related: Proneness.
prong (n.)
early 15c., prange "pointed instrument;" mid-15c., pronge "pain," from Anglo-Latin pronga "prong, pointed tool," of unknown origin, perhaps related to Middle Low German prange "stick, restraining device," prangen "to press, pinch." See also prod, which might be related. Prong-horned antelope is from 1815 (short form pronghorn attested from 1826).
pronominal (adj.)
1670s, from Late Latin pronominalis (Priscian) "pertaining to a pronoun," from Latin pronomen (see pronoun).
pronoun (n.)
mid-15c., from pro- and noun; modeled on Middle French pronom, from Latin pronomen, from pro "in place of" + nomen "name, noun" (see name (n.)). A loan-translation of Greek antonymia.
pronounce (v.)
early 14c., "to declare officially;" late 14c., "to speak, utter," from Old French prononcier "declare, speak out, pronounce" (late 13c., Modern French prononcer), from Late Latin pronunciare, from Latin pronuntiare "to proclaim, announce; pronounce, utter," from pro "forth, out, in public" (see pro-) + nuntiare "announce," from nuntius "messenger" (from PIE root *neu- "to shout"). With reference to the mode of sounding words or languages, it is attested from 1620s (but see pronunciation in this sense from early 15c.). Related: Pronounced; pronouncing.
pronounceable (adj.)
1610s, from pronounce (v.) + -able.
pronounced (adj.)
"spoken," 1570s, past participle adjective from pronounce (v.). Sense of "emphatic" is a figurative meaning first attested c. 1730.
pronouncement (n.)
1590s, from pronounce + -ment.
pronto (adv.)
1850, from Spanish pronto, perhaps influenced by Italian pronto (borrowed by English 1740), both from Latin promptus (see prompt).
pronunciation (n.)
early 15c., "mode in which a word is pronounced," from Middle French prononciation and directly from Latin pronuntiationem (nominative pronuntiatio) "act of speaking, utterance, delivery," also "proclamation, public declaration," noun of action from past participle stem of pronuntiare "announce" (see pronounce).
proof (n.)
early 13c., preove "evidence to establish the fact of (something)," from Anglo-French preove, Old French prueve "proof, test, experience" (13c., Modern French preuve), from Late Latin proba "a proof," a back-formation from Latin probare "to prove" (see prove). "The devocalization of v to f ensued upon the loss of final e; cf. the relation of v and f in believe, belief, relieve, relief, behove, behoof, etc. [OED].

Meaning "act of proving" is early 14c. Meaning "act of testing or making trial of anything" is from late 14c., from influence of prove. Meaning "standard of strength of distilled liquor" is from 1705. In photography from 1855. Typographical sense of "trial impression to test type" is from c. 1600. Numismatic sense of "coin struck to test a die" is from 1762; now mostly in reference to coins struck from highly polished dies, mainly for collectors.

Adjectival sense (proof against) is recorded from 1590s, from the noun in expressions such as proof of (mid-15c.), hence extended senses involving "tested power" in compounds such as fireproof (1630s), waterproof (1725), foolproof (1902), etc. Shakespeare has shame-proof. Expression the proof is in the pudding (1915) is a curious perversion of earlier proof of the pudding is in the eating (1708), with proof in the sense "quality of proving good or turning out well" (17c.); perhaps an advertiser's condensed form of the original.
proof (v.)
1834, "to test," from proof (n.). From 1950 as short for proofread (v.). Related: Proofed; proofing.
proofread (v.)
also proof-read, 1878, back-formation from proofreader. Related: Proofread; Proofreading.
proofreader (n.)
also proof-reader, 1808, from proof (n.) in the typographical sense + reader.
prop (n.1)
"support," mid-15c., from Middle Dutch proppe "vine prop, support," of unknown origin. Probably related to Old High German pfropfo, German pfropfen "to prop," perhaps from Latin propago "a set, layer of a plant" (see propagation). Irish propa, Gaelic prop are from English.
prop (n.2)
"object used in a play," 1898, from props (1841), shortened form of properties (which was in theatrical use from early 15c.). Props as slang shortening for proper respects (or something similar) appeared c. 1999.
prop (v.)
"to support," mid-15c., probably from prop (n.1) or a related verb in Dutch. Related: Propped; propping.
prop (n.3)
short for propeller, 1914.
propaedeutic (n.)
1798, from Greek propaideuein "to teach beforehand," from pro "before" (see pro-) + paideuein "to teach," which is related to the root of pedagogue. From 1849 as an adjective.
propaganda (n.)
1718, "committee of cardinals in charge of Catholic missionary work," short for Congregatio de Propaganda Fide "congregation for propagating the faith," a committee of cardinals established 1622 by Gregory XV to supervise foreign missions. The word is properly the ablative fem. gerundive of Latin propagare (see propagation). Hence, "any movement to propagate some practice or ideology" (1790). Modern political sense dates from World War I, not originally pejorative. Meaning "material or information propagated to advance a cause, etc." is from 1929.
propagandist (n.)
1797, from propaganda + -ist. Related: Propagandistic.
propagandize (v.)
1841, from propaganda + -ize. Related: Propagandized; propagandizing.
propagate (v.)
1560s, "to cause to multiply," from Latin propagatus, past participle of propagare "set forward, extend, spread, increase; multiply plants by layers, breed," from propago (genitive propaginis) "that which propagates, offspring," from pro "forth" (see pro-) + second element from PIE root *pag- "to fasten," source of pangere "to fasten" (see pact). Intransitive sense "reproduce one's kind" is from c. 1600. Related: Propagated; propagating.
propagation (n.)
mid-15c., from Old French propagacion "offshoot, offspring" (13c.) and directly from Latin propagationem (nominative propagatio) "a propagation, extension, enlargement," noun of action from past participle stem of propagare "set forward, extend, spread, increase; multiply plants by layers, breed," from propago (genitive propaginis) "that which propagates, offspring," from pro "forth" (see pro-) + second element from PIE root *pag- "to fasten," source of pangere "to fasten" (see pact).
propane (n.)
"colorless gas occurring in petroleum," 1866, with chemical suffix -ane + prop(ionic acid) (1850), from French propionique (1847), from Greek pro "forward" (see pro-) + pion "fat" (see fat (adj.)), in reference to its being first in order of the fatty acids.
propel (v.)
mid-15c., "to drive away, expel," from Latin propellere "push forward, drive forward, drive forth; move, impel," from pro "forward" (see pro-) + pellere "to push, drive" (from PIE root *pel- (5) "to thrust, strike, drive"). Meaning "to drive onward, cause to move forward" is from 1650s. Related: Propelled; propelling.
propellant (n.)
less-etymological, but more usual, spelling of propellent; 1881 as a firearm explosive; 1919 as "fuel for a rocket engine."
propellent (adj.)
1640s, from propel + -ent. As a noun from 1814.
propeller (n.)
1780, "anything that propels," agent noun from propel. In mechanical sense, 1809, of ships; of flying machines (in a broad, theoretical sense) 1842, in the specific modern sense 1853.
propensity (n.)
1560s, "disposition to favor," with -ty + obsolete adjective propense "inclined, prone" (1520s), from Latin propensus, past participle of propendere "incline to, hang forward, hang down, weigh over," from pro "forward" (see pro-) + pendere "to hang, cause to hang; weigh" (from PIE root *(s)pen- "to draw, stretch, spin").
proper (adj.)
c. 1300, "adapted to some purpose, fit, apt; commendable, excellent" (sometimes ironic), from Old French propre "own, particular; exact, neat, fitting, appropriate" (11c.), from Latin proprius "one's own, particular to itself," from pro privo "for the individual, in particular," from ablative of privus "one's own, individual" (see private (adj.)) + pro "for" (see pro-). Related: Properly.

From early 14c. as "belonging or pertaining to oneself; individual; intrinsic;" from mid-14c. as "pertaining to a person or thing in particular, special, specific; distinctive, characteristic;" also "what is by the rules, correct, appropriate, acceptable." From early 15c. as "separate, distinct; itself." Meaning "socially appropriate, decent, respectable" is first recorded 1704. Proper name "name belonging to or relating to the person or thing in question," is from late 13c., a sense also preserved in astronomical proper motion (c. 1300). Proper noun is from c. 1500.
propertied (adj.)
"holding property," 1760, from property (n.).
property (n.)
c. 1300, properte, "nature, quality," later "possession, thing owned" (early 14c., a sense rare before 17c.), from an Anglo-French modification of Old French propriete "individuality, peculiarity; property" (12c., Modern French propreté; see propriety), from Latin proprietatem (nominative proprietas) "ownership, a property, propriety, quality," literally "special character" (a loan-translation of Greek idioma), noun of quality from proprius "one's own, special" (see proper). For "possessions, private property" Middle English sometimes used proper goods. Hot property "sensation, a success" is from 1947 in "Billboard" stories.
prophase
1884, from German prophase (Strasburger, 1884); see pro- + phase.
prophecy (n.)
c. 1200, prophecie, prophesie, "function of a prophet," from Old French profecie (12c. Modern French prophétie) and directly from Late Latin prophetia (source also of Spanish profecia, Italian profezia), from Greek propheteia "gift of interpreting the will of the gods," from prophetes (see prophet). Meaning "thing spoken or written by a prophet" is from c. 1300.
prophesy (v.)
mid-14c., prophecein, prophesein, from Old French prophecier (13c.), from prophecie (see prophecy). The noun and verb spellings were not fully differentiated until 18c. Related: Prophesied; prophesying.
prophet (n.)
late 12c., "person who speaks for God; one who foretells, inspired preacher," from Old French prophete, profete "prophet, soothsayer" (11c., Modern French prophète) and directly from Latin propheta, from Greek prophetes (Doric prophatas) "an interpreter, spokesman," especially of the gods, "inspired preacher or teacher," from pro "before" (from PIE root *per- (1) "forward," hence "in front of, before") + root of phanai "to speak," from PIE root *bha- (2) "to speak, tell, say."

The Greek word was used in Septuagint for Hebrew nabj "soothsayer." Early Latin writers translated Greek prophetes with Latin vates, but the Latinized form propheta predominated in post-Classical times, chiefly due to Christian writers, probably because of pagan associations of vates. In English, meaning "prophetic writer of the Old Testament" is from late 14c. Non-religious sense is from 1848; used of Muhammad from 1610s (translating Arabic al-nabiy, and sometimes also al-rasul, properly "the messenger"). The Latin word is glossed in Old English by witga.
prophetess (n.)
c. 1300, from prophet + -ess.
prophetic (adj.)
late 15c., from Middle French prophétique (15c.) and directly from Late Latin propheticus, from Greek prophetikos "pertaining to a prophet, oracular," from prophetes (see prophet). Related: Prophetical (mid-15c.); prophetically.
prophylactic (adj.)
1570s, originally of medicines, "that tends to prevent disease," from Middle French prophylactique (16c.) and directly as a Latinized borrowing of Greek prophylaktikos "precautionary," from prophylassein "keep guard before, ward off, be on one's guard," from pro "before" (see pro-) + phylassein, Ionic variant of phylattein "to watch over, to guard," but also "cherish, keep, remain in, preserve," from phylax "guard," a word of unknown origin.

The noun is first recorded 1640s, "a medicine or treatment to prevent disease;" meaning "condom" is from 1943, replacing earlier preventive (1822), preventative (1901). Condoms originally were used more to thwart contagious disease than to prevent pregnancy.
prophylaxis (n.)
"preventive treatment of disease," 1746, Modern Latin, from Greek pro "before" (see pro-) + phylaxis "a watching, guarding" (see prophylactic).
propinquity (n.)
late 14c., "nearness in relation, kinship," later also "physical nearness" (early 15c.), from Old French propinquite (13c.) and directly from Latin propinquitatem (nominative propinquitas) "nearness, vicinity; relationship, affinity," from propinquus "near, neighboring," from prope "near" (enlarged from PIE *pro "before," from root *per- (1) "forward," hence "in front of, toward, near") + suffix -inquus.
Nothing propinks like propinquity [Ian Fleming, chapter heading, "Diamonds are Forever," 1956; phrase popularized 1960s by U.S. diplomat George Ball]
propitiate (v.)
1580s, a back-formation from propritiation and in part from propitiate (adj.), from Latin propitiatus, past participle of propitiare "appease, propitiate" (see propitiation). Related: Propitiated; propitiating; propitiatingly; propitiable (1550s).
propitiation (n.)
late 14c., from Late Latin propitiationem (nominative propitiatio) "an atonement," noun of action from past participle stem of Latin propitiare "appease, propitiate," from propitius "favorable, gracious, kind, well-disposed," from pro- "forward" (see pro-) + stem related to petere "to make for, go to; seek, strive after; ask for, beg, beseech, request" (see petition (n.)).

The sense in Latin is perhaps because the word originally was religious, literally "a falling or rushing toward," hence "eager," and, of the gods, "well-disposed." Earliest recorded form of the word in English is propitiatorium "the mercy seat, place of atonement" (c. 1200), translating Greek hilasterion.
propitiatory
c. 1300 (n.) "the mercy seat," from Late Latin propitiatorium (translating Greek hilasterion in Bible); noun use of neuter singular of propitiatorius "atoning, reconciling," from propitiatus, past participle of propitiare (see propitiation). As an adjective in English from 1550s.
propitious (adj.)
mid-15c., from Anglo-French propicius, Old French propicius "gracious, favorable, useful" (12c., Modern French propice) and directly from Latin propitius "favorable, kind, gracious, well-disposed" (see propitiation). Earlier English form was propice, from Old French propice. Related: Propitiously.
propone (v.)
"propose," late 14c., from Latin proponere "to put forth" (see propound). Related: Proponed; proponing; proponement.
proponent (n.)
1580s, "one who brings forth a proposition or argument," from Latin proponentem (nominative proponens), present participle of proponere "put forward" (see propound). In part also a native formation from propone. As an adjective from 1680s.
proport (v.)
late 14c., from Old French proporter (12c.), variant of porporter (see purport).
proportion (v.)
"to adjust or regulate the proportions of," late 14c., from proportion (n.) and in part from Middle French proporcioner and directly from Medieval Latin proportionare. Related: Proportioned; proportioning.