Online Etymology Dictionary

proportionality (n.): 1560s, from French proportionalité (14c.) or directly from Medieval Latin proportionalitas, from proportio (see proportion).
proportionate (adj.): late 14c., "of proper proportion," from Medieval Latin proportionatus "proportioned," past participle of proportionare (see proportion (n.)). Related: Proportionately.
proposal (n.): 1650s, from propose + -al (2); specific sense of "offer of marriage" is from 1749.
propose (v.): mid-14c., from Old French proposer "propose, advance, suggest" (12c.), from pro- "forth" (see pro-) + poser "put, place" (see pose (v.1)). Meaning "make an offer of marriage" is first recorded 1764. Related: Proposed; proposing. See also propone, which coexisted with this word for a time.
proposition (n.): mid-14c., "a setting forth as a topic for discussion," from Old French proposicion "proposal, submission, (philosophical) proposition" (12c.), from Latin propositionem (nominative propositio) "a setting forth, statement, a presentation, representation; fundamental assumption," noun of action from past participle stem of proponere (see propound). Meaning "action of proposing something to be done" is from late 14c. General sense of "matter, problem, undertaking" recorded by 1877. Related: Propositional.
proposition (v.): 1914, from proposition (n.); specifically of sexual favors from 1936. Related: Propositioned; propositioning.
propound (v.): late 16c. variant of Middle English proponen "to put forward" (late 14c.), from Latin proponere "put forth, set forth, lay out, display, expose to view," figuratively "set before the mind; resolve; intend, design," from pro- "before" (see pro-) + ponere "to put" (see position (n.)). Perhaps influenced in form by compound, expound; also compare pose (v.). Related: Propounded; propounding.
proprietary (adj.): mid-15c., "possessing worldly goods in excess of a cleric's needs," from Medieval Latin proprietarius "owner of property," noun use of Late Latin adjective proprietarius "of a property holder," from Latin proprietas "owner" (see property). Meaning "held in private ownership" is first attested 1580s. The word was used earlier in English as a noun meaning "proprietor," also "worldly person" (c. 1400), from a noun use in French and Medieval Latin.
proprietor (n.): 1630s, "owner, by royal grant, of an American colony," probably from proprietary (n.) in sense "property owner" (late 15c., see proprietary). In general sense of "one who holds something as property" it is attested from 1640s.
propriety (n.): mid-15c., "proper character, disposition," from Old French proprieté "individuality, peculiarity; property" (12c.), from Latin proprietatem (nominative proprietas) "appropriateness," also "ownership" (see property). Meaning "fitness, appropriateness" is attested from 1610s; sense of "conformity to good manners" is from 1782.
proprioception (n.): 1906, from proprioceptor, from Latin proprius "own" (see proper) + reception. Coined by English neurophysiologist C.S. Sherrington (1857-1952). Related: Proprioceptive; proprioceptor.
propulsion (n.): 1610s, "expulsion," noun of action formed from propuls-, past participle stem of Latin propellere "to propel" (see propel). Meaning "act of driving forward, propulsive force" first attested 1799.
propulsive (adj.): 1640s, from propuls-, past participle stem of Latin propellere "to propel" (see propel) + -ive.
prorate (v.): also pro-rate, "divide proportionally," 1860, American English, verb derived from Latin pro rata (parte) (see pro rata). Related: Prorated; prorating.
proration (n.): 1893, noun of action from prorate (v.).
prorogue (v.): early 15c., "to prolong, extend," from Old French proroger, proroguer (14c.), from Latin prorogare, literally "to ask publicly," from pro "before" (see pro-) + rogare "to ask" (see rogation). Perhaps the original sense in Latin was "to ask for public assent to extending someone's term in office." Legislative meaning "discontinue temporarily" is attested from mid-15c. Related: Prorogation.
prosaic (adj.): 1650s, "having to do with prose," from Middle French prosaique and directly from Medieval Latin prosaicus "in prose" (16c.), from Latin prosa "prose" (see prose). Meaning "having the character of prose (in contrast to the feeling of poetry)" is by 1746; extended sense of "ordinary" is by 1813, both from French.
proscenium (n.): c. 1600, "stage of an ancient theater," from Latin proscaenium, from Greek proskenion "the space in front of the scenery," also "entrance of a tent," from pro "in front" (see pro-) + skene "stage, tent, booth" (see scene). Modern sense of "space between the curtain and the orchestra" is attested from 1807.
prosciutto (n.): Italian spiced ham, 1911, from Italian, alteration (probably by influence of prosciugato "dried") of presciutto, from pre-, here an intensive prefix, + -sciutto, from Latin exsuctus "lacking juice, dried up," past participle of exsugere "suck out, draw out moisture," from ex- "out" (see ex-) + sugere "to suck" (see sup (v.2)).
proscribe (v.): early 15c., "write before, prefix," from Latin proscribere "publish in writing" (literally "write in front of"), including senses of "publish as having forfeited one's property, condemn, outlaw before the world," from pro- "before" (see pro-) + scribere "to write" (see script (n.)). Meaning "prohibit as wrong or dangerous" first recorded 1620s.
proscription (n.): late 14c., "decree of condemnation, outlawry," from Latin proscriptionem (nominative proscriptio) "a public notice (of sale); proscription, outlawry, confiscation," noun of action from past participle stem of proscribere (see proscribe).
proscriptive (adj.): 1757, from Latin proscript-, past participle stem of proscribere (see proscribe) + -ive. Related: Proscriptively.
prose (n.): c. 1300, "story, narration," from Old French prose (13c.), from Latin prosa oratio "straightforward or direct speech" (without the ornaments of verse), from prosa, fem. of prosus, earlier prorsus "straightforward, direct," from Old Latin provorsus "(moving) straight ahead," from pro- "forward" (see pro-) + vorsus "turned," past participle of vertere "to turn" (see verse).
"Good prose, to say nothing of the original thoughts it conveys, may be infinitely varied in modulation. It is only an extension of metres, an amplification of harmonies, of which even the best and most varied poetry admits but few." [Walter Savage Landor, "Imaginary Conversations"]
Meaning "prose writing; non-poetry" is from mid-14c. The sense of "dull or commonplace expression" is from 1680s, out of earlier sense "plain expression" (1560s). Those who lament the want of an English agent noun to correspond to poet might try prosaist (1776), proser (1620s), or Frenchified prosateur (1880), though the first two in their day also acquired in English the secondary sense "dull writer."
prosecute (v.): early 15c., "follow up, pursue" (some course or action), from Latin prosecutus, past participle of prosequi "follow after, accompany; chase, pursue; attack, assail, abuse" (see pursue). Meaning "bring to a court of law" is first recorded 1570s. Meaning "go into detail" is from 1530s.
prosecution (n.): 1560s, "action of pursuing," from Middle French prosecution (late 13c.) and directly from Late Latin prosecutionem (nominative prosecutio) "a following," noun of action from past participle stem of prosequi (see prosecute). Meaning "legal action" is from 1630s.
prosecutor (n.): 1590s, from Medieval Latin prosecutor, agent noun from prosequi (see prosecute). Specific legal sense of "one who brings a case in a court of law" is from 1620s; earlier such a person was a promoter (late 15c.). Related: Prosecutorial.
proselyte (n.): late 14c., from Old French proselite (13c., Modern French prosélyte), from Late Latin proselytus, from Greek proselytos "convert (to Judaism), stranger, one who has come over," noun use of adjective meaning "having arrived," from second aorist stem of proserkhesthai "to come or go; surrender; associate with," from proti "toward" + root of eleusesthai "to be going to come," from PIE *elu-to-, from root *leudh- "to go." Originally in English "a Gentile converted to Judaism" (late 14c.).
proselytise (v.): chiefly British English spelling of proselytize (q.v.). For suffix, see -ize. Related: Proselytised; proselytising.
proselytism (n.): 1650s, from proselyte + -ism.
proselytization (n.): 1846, from proselytize + -ation.
proselytize (v.): 1670s, "to make proselytes," from proselyte + -ize. Related: Proselytized; proselytizing.
proselytizer (n.): 1811, agent noun from proselytize.
Proserpina: daughter of Ceres and wife of Pluto, Latin (or Etruscan) modification of Greek Persephone, perhaps influenced by Latin proserpere "to creep forth" on notion of the germination of plants.
prosify (v.): 1774, from prose + -ify. Related: Prosified; prosifying.
prosiness (n.): 1814, from prosy + -ness.
prosit (interj.): 1846, toast or expression wishing good health (from 16c., famously a drinking pledge by German students), Latin, literally "may it advantage (you)," third person singular present subjunctive of prodesse "to do good, be profitable" (see proud).
prosodemic (adj.): 1964, with -ic + prosodeme (1940), from Greek proso-, probably related to pros "toward, to, at, against, near."
prosody (n.): late 15c., from Latin prosodia "accent of a syllable," from Greek prosoidia "song sung to music," also "accent, modulation," literally "a singing in addition to," from pros "to, forward, near" + oide "song, poem" (see ode). Related: Prosodiacal; prosodist.
prosopagnosia (n.): 1950, Medical Latin from German prosopagnosie (1948), from Greek prosopon "face" (see prosopopeia) + agnosia "ignorance" (see agnostic).
prosopopeia (n.): also prosopopoeia, 1560s, from Latin prosopopoeia, from Greek prosopopoiia "the putting of speeches into the mouths of others," from prosopon "person, face" (literally "that which is toward the eyes," from pros "to" + ops "eye, face;" see eye (n.)) + poiein "make" (see poet). Generally, a rhetorical figure in which an imaginary or absent person is made to speak or act.
prospect (n.): early 15c., "act of looking into the distance," from Latin prospectus "distant view, look out; sight, faculty of sight," noun use of past participle of prospicere "look out on, look forward," from pro- "forward" (see pro-) + specere "look at" (see scope (n.1)). Meaning "extensive view of the landscape" is from 1530s; transferred sense of "mental view or survey" is from 1620s. Sense of "person or thing considered promising" is from 1922. Prospects "expectations, things looked forward to" is from 1660s.
prospect (v.): "explore for gold, examine land with a view to a mining claim," 1841, from prospect (n.) in specialized sense of "spot giving prospects of ore" (1832). Earlier in a sense "look forth, look out over" (1550s), from Latin prospectare. Related: Prospected; prospecting.
prospective (adj.): 1580s, from obsolete French prospectif and directly from Medieval Latin prospectivus "affording a prospect; pertaining to a prospect," from Latin prospect-, past participle stem of prospicere (see prospect (n.)). In 17c. also as a noun, "spy glass, telescope." Related: Prospectively.
prospector (n.): also prospecter, 1846 in the mining sense; agent noun from prospect (v.).
prospectus (n.): 1765, from French prospectus (1723) and directly from Latin prospectus "view" (see prospect (n.)).
prosper (v.): mid-14c., from Old French prosperer (14c.) and directly from Latin prosperare "cause to succeed, render happy," from prosperus "favorable, fortunate, prosperous," perhaps literally "agreeable to one's wishes," traditionally regarded as from Old Latin pro spere "according to expectation, according to one's hope," from pro "for" + ablative of spes "hope," from PIE root *spe- "to flourish, succeed, thrive, prosper" (see speed (n.)).
prosperity (n.): c. 1200, from Old French prosprete (12c., Modern French prospérité) and directly from Latin prosperitatem (nominative prosperitas) "good fortune," from prosperus (see prosper).
prosperous (adj.): early 15c., "tending to bring success," from prosper + -ous, or else from obsolete Middle French prospereus (15c.), from prosperer. The sense of "flourishing" is first recorded late 15c.
prostaglandin (n.): 1936, from German (1935); see prostate + gland + chemical suffix -in (2).
prostate (n.): 1640s, from Middle French prostate, from Medieval Latin prostata "the prostate," from Greek prostates (aden) "prostate (gland)," from prostates "leader, ruler, guardian; one standing in front," from proistanai "set before," from pro- "before" (see pro-) + histanai "cause to stand" from PIE root *stā- "to stand" (see stet). So called from its position at the base of the bladder.