Online Etymology Dictionary

pirouette (v.): 1822, from pirouette (n.) and also from French pirouetter. Related: Pirouetted; pirouetting.
pis aller (n.): "last resource, what one would do at the worst," 1670s, French, literally "to go worse," from pis "worse," from Latin peius, neuter of peior "worse" (see pejorative) + aller "to go."
Pisa: Italian city, from Etruscan, of uncertain meaning. Related: Pisan.
piscatology (n.): 1867, a hybrid from Latin piscatus, past participle of piscari "to fish," from pisces "a fish" (see fish (n.)) + -ology.
piscatorial (adj.): 1750, from piscatory + -ial.
piscatory (adj.): 1630s, from Latin piscatorius "of fishermen," from piscator "fisherman," from piscari "to fish," from pisces "a fish" (see fish (n.)).
Pisces (n.): 12th sign of the zodiac, late Old English, from Latin pisces, from plural of piscis "a fish," cognate with Gothic fisks, Old English fisc (see fish (n.)). Applied to persons born under this sign from 1924.
piscine (n.): c.1300, "reservoir, bathing pool," from Old French piscine "fishpond," from Latin piscina, from piscis "a fish" (see fish (n.)). Ecclesiastical sense is from late 15c., from Medieval Latin piscina. As an adjective from 1799.
piscivorous (adj.): 1660s, from Latin piscis "fish" (see fish (n.)) + -vorous.
Pisgah: 1640s, name of the mountain east of the River Jordan, whence Moses was allowed to view the Promised Land he could not enter (Deut. iii:27); with figurative extension. From Hebrew, literally "cleft."
pish: exclamation of contempt, attested from 1590s.
pismire (n.): "ant," late 14c. (early 14c. as a surname), from pyss "urine" (said to be in reference to the acrid smell of an anthill) + mire "an ant," probably from Old Norse maurr "ant" (cf. Swedish myra, Danish myre, Middle Dutch miere, Dutch mier, Crimean Gothic miera "ant"), from PIE base *morwi- (see Formica (2)). Cf. pissant, also early Dutch mierseycke (from seycke "urine"), Finnish kusiainen (from kusi "urine").
He is as angry as a pissemyre,
Though þat he haue al that he kan desire.
[Chaucer]
Applied contemptuously to persons from 1560s.
piss (v.): late 13c., from Old French pissier "urinate" (12c.), from Vulgar Latin *pissiare, of imitative origin. To piss away (money, etc.) is from 1948. Related: Pissed; pissing. Pissing while (1550s) once meant "a short time."
He shall not piss my money against the wall; he shall not have my money to spend in liquor. ["Dictionary of Buckish Slang, University Wit and Pickpocket Eloquence," London, 1811]
piss (n.): late 14c., from piss (v.). As a pure intensifier (piss-poor, piss-ugly, etc.) it dates from World War II. Piss and vinegar first attested 1942. Piss-prophet "one who diagnosed diseases by inspection of urine" is attested from 1620s. Piss proud "erect upon awakening" is attested from 1796.
piss off (v.): (intransitive) "go away," 1958, chiefly British; (transitive) "annoy," 1968, chiefly U.S.; from piss (v.) + off. Pissed off "angry, fed up" is 1946, U.S. slang.
piss-pot (n.): mid-15c.,from piss + pot (n.1).
pissant (n.): 1660s, "an ant," from first element of pismire (q.v.) + ant. Meaning "contemptible, insignificant person" is from 1903.
"[B]y sun-down [the gals] come pourin out of the woods like pissants out of an old log when tother end's afire." ["Dick Harlan's Tennessee Frolic," in collection "A Quarter Race in Kentucky," Philadelphia, 1846]
pissed (adj.): 1929, "drunk," past participle adjective from piss (v.). From 1946 as "angry," from piss off.
pissy (adj.): 1926, from piss + -y (2). Figurative use by 1972.
pistachio (n.): 1590s, from Italian pistacchio, from Latin pistacium "pistachio nut," from Greek pistakion "pistachio nut," from pistake "pistachio tree," from Persian pistah "pistachio." Borrowed earlier (1530s) as pystace, from Old French form pistace (13c.), which also is from the Italian word.
piste (n.): also pist, 1727, from French piste, from Latin pista (via) "beaten (track)," from pistus, past participle of pinsere "to pound, stamp" (see pestle).
pistil (n.): "female organ of a flower," 1718, from French pistil, from Modern Latin pistillum "a pistil," so called from resemblance to a pestle, from Latin pistillum "pestle" (see pestle). Related: Pistillary; pistillaceous; pistillate; pistilline.
pistle (n.): "letter," Old English pistol, a shortening of epistol, from Latin epistola (see epistle).
pistol (n.): "small hand-held firearm," 1570s, from Middle French pistole "short firearm" (1566), of uncertain origin, sometimes said to be from German Pistole, from Czech pis'tala "firearm," literally "tube, pipe," from pisteti "to whistle," of imitative origin, related to Russian pischal "shepherd's pipe."

But earlier English form pistolet (1550) is said to be from Middle French pistolet "a small firearm," also "a small dagger," which may be the literal sense; though some connect this word with Italian pistolese, in reference to Pistoia, town in Tuscany noted for gunsmithing. Pistol-whip (v.) is first recorded 1942.
pistole (n.): former Spanish coin (not called that in Spanish), 1590s, from French pistole, from Italian piastola, diminutive of piastra "plate or leaf of metal" (see piaster). Cf. earlier pistolet (1550s) "foreign coin," which OED says is from French pistolet "short firearm" (see pistol) and so called for being smaller and thinner than other coins.
pistolero (n.): 1937, from Spanish; see pistolier.
pistolier (n.): also pistoleer, 1570s from obsolete French pistolier, from pistole (see pistol).
piston (n.): 1704, from French piston, from Middle French piston "large pestle," from Old Italian pistone "a piston," variant of pestone "a pestle," from pestare "to pound," from Late Latin pistare, frequentative of Latin pinsere (past participle pistus) "to pound" (see pestle). As a verb from 1930.
pit (n.1): "hole, cavity," Old English pytt "water hole, well; pit, grave," from West Germanic *puttjaz "pool, puddle" (cf. Old Frisian pet, Old Saxon putti, Old Norse pyttr, Middle Dutch putte, Dutch put, Old High German pfuzza, German Pfütze "pool, puddle"), early borrowing from Latin puteus "well, pit, shaft." Meaning "abode of evil spirits, hell" is attested from early 13c. Pit of the stomach (1650s) is from the slight depression there between the ribs.
pit (v.): mid-15c., "to put into a pit," from pit (n.1); especially for purposes of fighting (of cocks, dogs, pugilists) from 1760. Figurative sense of "to set in rivalry" is from 1754. Meaning "to make pits in" is from late 15c. Related: Pitted; pitting. Cf. Pit-bull as a dog breed attested from 1922, short for pit-bull terrier (by 1912). This also is the notion behind the meaning "the part of a theater on the floor of the house" (1640s).
pit (n.2): "hard seed," 1841, from Dutch pit "kernel, seed, marrow," from Middle Dutch pitte, ultimately from West Germanic *pithan-, source of pith (q.v.).
pit-a-pat (adv.): also pitter-pat, 1520s; imitative. As a noun from 1580s.
pita (n.): "thick, flat bread," 1951, from Modern Hebrew pita or Modern Greek petta "bread," perhaps from Greek peptos "cooked," or somehow connected to pizza (q.v.).
pitch (n.2): "resinous substance, wood tar," late 12c., pich, from Old English pic "pitch," from a Germanic borrowing (cf. Old Saxon and Old Frisian pik, Middle Dutch pik, Dutch pek, Old High German pek, German Pech, Old Norse bik) from Latin pix (genitive picis) "pitch," from PIE root *pi- "sap, juice" (cf. Greek pissa, Lithuanian pikis, Old Church Slavonic piklu "pitch;" see pine (n.)). Applied to pine resins from late 14c. Pitch-black is attested from 1590s; pitch-dark from 1680s.
pitch (v.1): c.1200, "to thrust in, fasten, settle," probably from an unrecorded Old English *piccean, related to prick (v.). The original past tense was pight. Sense of "set upright," as in pitch a tent (late 13c.), is from notion of "driving in" the pegs. Meaning to incline forward and downward" is from 1510s. Meaning "throw (a ball)" evolved late 14c. from that of "hit the mark." Musical sense is from 1670s. Of ships, "to plunge" in the waves, 1620s. To pitch in "work vigorously" is from 1847, perhaps from farm labor. Related: Pitched; pitching.
pitch (n.1): 1520s, "something that is pitched," from pitch (v.1). Meaning "act of throwing" is attested from 1833. Meaning "act of plunging headfirst" is from 1762; sense of "slope, degree, inclination" is from 1540s; musical sense is from 1590s; but the connection of these is obscure. Sales pitch in the modern commercial advertising sense is from 1943, American English, perhaps from the baseball sense.
pitch (v.2): "to cover with pitch," Old English pician, from the source of pitch (n.2).
pitch-pipe (n.): 1711, from pitch (n.) in the musical sense + pipe (n.1).
pitchblende (n.): also pitch-blende, 1770, a loan-translation of German Pechblende; see pitch (n.2) + blende.
pitcher (n.1): "earthen jug," c.1200, from Old French pichier (12c.), altered from bichier, from Medieval Latin bicarium, probably from Greek bikos "earthen vessel" (see beaker). Pitcher-plant is recorded from 1819; so called for its resemblance.
pitcher (n.2): "one who pitches," 1722, agent noun from pitch (v.1). Originally of one tossing hay into a wagon, etc.; baseball sense first recorded 1845.
pitchfork (n.): mid-14c., altered (by influence of pichen "to throw, thrust;" see pitch (v.1)) from Middle English pic-forken (c.1200), from pik (see pike (n.4)) + fork (n.). The verb is attested from 1837.
pitchman (n.): 1926, American English, from pitch (n.1) in the sales sense + man (n.).
piteous (adj.): c.1300, from Anglo-French pitous, Old French pitos "pious; merciful, compassionate, moved to pity; pitiful" (12c., Modern French piteux), from Medieval Latin pietosus "merciful, pitiful," in Vulgar Latin "dutiful," from Latin pietas "dutiful conduct, compassion" (see piety). Related: Piteously; piteousness.
pitfall (n.): c.1300, "concealed hole," a type of animal trap, from pit (n.1) + fall (n.). Extended sense of "any hidden danger" is first recorded early 15c.
pith (n.): Old English piþa "pith of plants," also "essential part," from West Germanic *pithan- (cf. Middle Dutch pitte, Dutch pit, East Frisian pit), a Low German root of uncertain origin. Figurative sense was in Old English. Pith helmet (1889, earlier pith hat, 1884) so called because it is made from the dried pith of the Bengal spongewood.
pith (v.): "to kill by piercing the spinal cord," 1805, from pith (n.). Related: Pithed; pithing.
pithecanthropus (n.): genus of extinct primates, 1895, from Modern Latin, literally "monkey-man," from Greek pithekos "ape" + anthropos "man" (see anthropo-). Coined 1868 by Haeckel as a name for a hypothetical link between apes and men (attested in English in this sense from 1876); applied by Dr. Eugène Dubois (1858-1940), physician of the Dutch army in Java, to remains he found there in 1891.
pitheco-: before vowels pithec-, word-forming element meaning "pertaining to an ape or monkey," from Greek pithekos "ape."
pithy (adj.): early 14c., "strong, vigorous," from pith (n.) + -y (2). Meaning "full of substance or significance" is from 1520s; literal meaning "full of pith" not attested until 1560s. Related: Pithily; pithiness.