posh (adj.) Look up posh at Dictionary.com
by 1914 (1903 as push), of uncertain origin; no evidence for the common derivation from an acronym of port outward, starboard home, supposedly the shipboard accommodations of wealthy British traveling to India on the P & O Lines (to keep their cabins out of the sun); as per OED, see objections outlined in G. Chowdharay-Best, "Mariner's Mirror," Jan. 1971; also see here. The acronym story dates from 1955. More likely from slang posh "a dandy" (1890), from thieves' slang meaning "money" (1830), originally "coin of small value, halfpenny," possibly from Romany posh "half" [Barnhart].
The cavalryman, far more than the infantryman, makes a point of wearing "posh" clothing on every possible occasion -- "posh" being a term used to designate superior clothing, or articles of attire other than those issued by and strictly conforming to the regulations. [E. Charles Vivian, "The British Army From Within," London, 1914]
posit (v.) Look up posit at Dictionary.com
"to assert," 1690s, from Latin positus "placed, situated, standing, planted," past participle of ponere "put, place" (see position (n.)). Related: Posited; positing.
position (n.) Look up position at Dictionary.com
late 14c., as a term in logic and philosophy, from Old French posicion "position, supposition" (Modern French position), from Latin positionem (nominative positio) "act or fact of placing, situation, position, affirmation," noun of state from past participle stem of ponere "put, place," from PIE *po-s(i)nere, from *apo- "off, away" (see apo-) + *sinere "to leave, let" (see site).

Meaning "proper place occupied by a person or thing" is from 1540s. Meaning "manner in which some physical thing is arranged or posed" first recorded 1703; specifically in reference to dance steps, 1778, sexual intercourse, 1883. Meaning "official station, employment" is from 1890.
position (v.) Look up position at Dictionary.com
1670s, "to assume a position (intransitive), from position (n.). Transitive sense of "to put in a particular position" is recorded from 1817. Related: Positioned; positioning.
positional (adj.) Look up positional at Dictionary.com
1570s, from position (n.) + -al (1).
positive (adj.) Look up positive at Dictionary.com
early 14c., originally a legal term meaning "formally laid down," from Old French positif (13c.) and directly from Latin positivus "settled by agreement, positive" (opposed to naturalis "natural"), from positus, past participle of ponere "put, place" (see position (n.)).

Sense of "absolute" is from mid-15c. Meaning in philosophy of "dealing only with facts" is from 1590s. Sense broadened to "expressed without qualification" (1590s), then "confident in opinion" (1660s); mathematical use is from 1704; in electricity, 1755. Psychological sense of "concentrating on what is constructive and good" is recorded from 1916.
positive (n.) Look up positive at Dictionary.com
1520s, from positive (adj.).
positively (adv.) Look up positively at Dictionary.com
mid-15c., "in a definite way," from positive (adj.) + -ly (2). Meaning "absolutely" is from 1777.
positivism (n.) Look up positivism at Dictionary.com
1847, the philosophy of Auguste Comte (1798-1857), who published "Philosophie positive" in 1830; see positive (adj.) in the "just the facts" sense + -ism. Related: Positivist; Positivistic.
positivity (n.) Look up positivity at Dictionary.com
1650s, from positive (adj.) + -ity.
positron (n.) Look up positron at Dictionary.com
1933, coined from posi(tive) (elec)tron.
posse (n.) Look up posse at Dictionary.com
1640s (in Anglo-Latin from early 14c.), shortening of posse comitatus "the force of the county" (1620s, in Anglo-Latin from late 13c.), from Medieval Latin posse "body of men, power," from Latin posse "have power, be able" (see potent) + comitatus "of the county," genitive of Late Latin word for "court palace" (see comitatus). Modern slang meaning "small gang" is probably from Western movies.
possess (v.) Look up possess at Dictionary.com
late 14c., "to hold, occupy, reside in" (without regard to ownership), a back formation from possession and in part from Old French possesser "to have and hold, take, be in possession of" (mid-13c.), from Latin possess-, past participle stem of possidere "to have and hold, possess, be master of, own," from posse "to be able," from potis "able, powerful" (see potent) + esse "to be" (see be). Meaning "to hold as property" is recorded from c. 1500. Demonic sense is recorded from 1530s (implied in possessed). Related: Possessed; possessing.
possessed (adj.) Look up possessed at Dictionary.com
"controlled by an indwelling demon," 1530s, past participle adjective from possess (v.).
possession (n.) Look up possession at Dictionary.com
mid-14c., "act or fact of possessing, a taking possession, occupation," also "thing possessed, that which is possessed," from Old French possession "fact of having and holding; what is possessed;" also "demonic possession," and directly from Latin possessionem (nominative possessio), noun of action from past participle stem of possidere "to possess" (see possess). Legal property sense is earliest; demonic sense first recorded 1580s. Phrase possession is nine (or eleven) points of the law is out of a supposed 10 (or 12). With eleven from 1640s; with nine from 1690s.
possessive (adj.) Look up possessive at Dictionary.com
mid-15c. (grammatical, also as a noun); 1550s in general use, from Middle French possessif (15c.) "relating to possession, possessive," and directly from Latin possessivus, from possess-, past participle stem of possidere "to possess" (see possess). Related: Possessively; possessiveness.
posset (n.) Look up posset at Dictionary.com
spiced drink of hot milk and liquor, mid-15c., of unknown origin.
possibility (n.) Look up possibility at Dictionary.com
late 14c., "condition of being possible," from Old French possibilité (13c.) and directly from Latin possibilitatem (nom. possibilitas) "possibility," from possibilis (see possible (adj.)). Meaning "a possible thing or substance" is from c. 1400. Related: Possibilities.
possible (adj.) Look up possible at Dictionary.com
mid-14c., from Old French possible and directly from Latin possibilis "that can be done," from posse "be able" (see potent).
possible (n.) Look up possible at Dictionary.com
1640s, from possible (adj.).
possibly (adv.) Look up possibly at Dictionary.com
c. 1400, from possible (adj.) + -ly (2).
POSSLQ Look up POSSLQ at Dictionary.com
1979, acronym from person of opposite sex sharing living quarters; it never was an official category.
possum (n.) Look up possum at Dictionary.com
1610s, shortened form of opossum. Phrase play possum is first recorded 1822.
post (adv.) Look up post at Dictionary.com
1540s, "with post horses," hence, "rapidly;" especially in the phrase to ride post "go rapidly," from post (n.3).
post (n.1) Look up post at Dictionary.com
"a timber set upright," from Old English post "pillar, doorpost," and Old French post "post, upright beam," both from Latin postis "door, post, doorpost," perhaps from por- "forth" (see pro-) + stare "to stand," from PIE root *sta- "to stand, set down, make or be firm" (see stet). Similar compound in Sanskrit prstham "back, roof, peak," Avestan parshti "back," Greek pastas "porch in front of a house, colonnade," Middle High German virst "ridepole," Lithuanian pirstas, Old Church Slavonic pristu "finger" (PIE *por-st-i-).
post (n.2) Look up post at Dictionary.com
"place when on duty," 1590s, from Middle French poste "place where one is stationed," also, "station for post horses" (16c.), from Italian posto "post, station," from Vulgar Latin *postum, from Latin positum, neuter past participle of ponere "to place, to put" (see position (n.)). Earliest sense in English was military; meaning "job, position" is attested 1690s.
post (n.3) Look up post at Dictionary.com
"mail system," c. 1500, "riders and horses posted at intervals," from post (n.2) on notion of riders and horses "posted" at intervals along a route to speed mail in relays, probably formed on model of Middle French poste in this sense (late 15c.). Meaning "system for carrying mail" is from 1660s.
post (v.4) Look up post at Dictionary.com
"to put up bail money," 1781, from one of the nouns post, but which one is uncertain. Related: Posted; posting.
post (v.1) Look up post at Dictionary.com
"to affix (a paper, etc.) to a post" (in a public place), hence, "to make known," 1630s, from post (n.1). Related: Posted; posting.
post (v.2) Look up post at Dictionary.com
in bookkeeping, "to transfer from a day book to a formal account," 1620s, from post (n.2) via a figurative sense of "carrying" by post horses. Related: Posted; posting.
post (v.3) Look up post at Dictionary.com
"to send through the postal system," 1837, from post (n.3). Earlier, "to travel with relays of horses" (1530s). Related: Posted; posting.
post (v.5) Look up post at Dictionary.com
"to station at a post," from post (n.2). Related: Posted; posting.
post factum Look up post factum at Dictionary.com
Latin, literally "after the fact," from factum "deed, act" (see fact).
post hoc Look up post hoc at Dictionary.com
Latin, "after this." Especially in post hoc, ergo propter hoc, logical fallacy, literally "after this, therefore because of this."
post meridiem Look up post meridiem at Dictionary.com
"after noon," 1640s, Latin, from post "after" (see post-) + accusative of meridies (see meridian).
post office (n.) Look up post office at Dictionary.com
1650s, "public department in charge of letter-carrying," from post (n.3) + office. Meaning "building where postal business is carried on" is from 1650s. In slang or euphemistic sense of "a sexual game" it refers to an actual parlor game first attested early 1850s in which pretend "letters" were paid for by kisses.
post restante Look up post restante at Dictionary.com
direction on mail that it be held at that post office until called for, French, literally "remaining post."
post- Look up post- at Dictionary.com
word-forming element meaning "after," from Latin post "behind, after, afterward," from *pos-ti (cognates: Arcadian pos, Doric poti "toward, to, near, close by;" Old Church Slavonic po "behind, after," pozdu "late;" Lithuanian pas "at, by"), from PIE *apo- (cognates: Greek apo "from," Latin ab "away from" see apo-).
post-bellum (adj.) Look up post-bellum at Dictionary.com
also postbellum, used in U.S. South from 1874 in reference to American Civil War; see post- + bellicose.
post-classical (adj.) Look up post-classical at Dictionary.com
1845, from post- + classical.
post-glacial (adj.) Look up post-glacial at Dictionary.com
1855, from post- + glacial.
post-graduate (adj.) Look up post-graduate at Dictionary.com
also postgraduate, 1858, originally American English, from post- + graduate (adj.). As a noun, attested from 1890. Abbreviation post-grad is recorded from 1950.
post-hole (n.) Look up post-hole at Dictionary.com
1703, from post (n.1) + hole (n.).
post-impressionism (n.) Look up post-impressionism at Dictionary.com
1910, from post- + impressionism.
Post-it (n.) Look up Post-it at Dictionary.com
1975, proprietary name.
post-millennial (adj.) Look up post-millennial at Dictionary.com
also postmillennial, 1831, from post- "after" + millennial; chiefly in reference to the Protestant doctrine that the second coming of Christ will occur after, not at, the Christian millennium.
post-modern (adj.) Look up post-modern at Dictionary.com
also post-modern, post modern, by 1919, in frequent use from 1949, from post- + modern.
But it has been only during the later decades of the modern era -- during that time interval that might fairly be called the post-modern era -- that this mechanistic conception of things has begun seriously to affect the current system of knowledge and belief; and it has not hitherto seriously taken effect except in technology and in the material sciences. [Thorstein Veblen, "The Vested Interests and the Common Man," 1919]

So much for the misapplied theory which has helped set the artist's nerves a-quiver and incited him to the extremes of post modern art, literary and other. [Wilson Follett, "Literature and Bad Nerves," "Harper's," June 1921]
Of architecture from 1940s; specific sense in the arts emerged 1960s (see postmodernism).
post-mortem (adj.) Look up post-mortem at Dictionary.com
also postmortem, 1734 (adverb), from Latin post mortem, from post "after" (see post-) + mortem, accusative of mors "death" (see mortal (adj.)). From 1835 as an adjective. As a noun, shortening of post-mortem examination, it is recorded from 1850.
post-operative (adj.) Look up post-operative at Dictionary.com
also postoperative, "occurring after a surgical operation," 1869, from post- + operative. Short form post-op is attested from 1971.
post-partum (adj.) Look up post-partum at Dictionary.com
also postpartum, 1837, "occurring after birth," from Latin post partum "after birth," from post "after" (see post-) + accusative of partus "a bearing, a bringing forth," from partus, past participle of parere "to bring forth" (see pare). Phrase Post-partum depression first attested 1929.