Online Etymology Dictionary

poncho (n.): type of blanket-like South American cloak, 1717, from American Spanish poncho, from Araucanian (Chile) pontho "woolen fabric," perhaps influenced by Spanish poncho (adj.), variant of pocho "discolored, faded."
pond (n.): c.1300 (mid-13c. in compounds), "artificially banked body of water," variant of pound "enclosed place" (see pound (n.2)). Applied locally to natural pools and small lakes from late 15c. Jocular reference to "the Atlantic Ocean" dates from 1640s.
ponder (v.): early 14c., "to estimate the worth of, to appraise," from Old French ponderer "to weigh, poise" (14c., Modern French pondérer) and directly from Latin ponderare "ponder, consider, reflect," literally "to weigh," from pondus (genitive ponderis) "weigh" (see pound (n.1)). Meaning "to weigh a matter mentally" is attested from late 14c. Related: Pondered; pondering; ponderation.
ponderance (n.): "weight, importance," 1798, from ponder + -ance.
ponderosa (n.): type of pine in western U.S., 1878, from scientific name Pinus ponderosa (1836), literally "heavy pine," from Latin ponderosus (see ponderous).
ponderous (adj.): c.1400, "thick;" early 15c., "heavy, weighty, clumsy," from Latin ponderosus "of great weight; full of meaning," from pondus (genitive ponderis) "weight" (see pound (n.1)). Meaning "tedious" is first recorded 1704. Related: Ponderously; ponderousness.
pone (n.): 1630s, "American Indian bread," earlier appone, ponap (1610s), from Powhatan (Algonquian) apan "something baked," from apen "she bakes." Later used in Southern U.S. for any type of cornbread.
pong (n.): by late 1960s as an abbreviation of ping-pong. The electronic arcade game (with capital P-) was released 1972.
Pongo (n.): ape genus, 1620s, from Kongo mpongi.
poniard (n.): 1580s, from Middle French poinard (early 16c.), from Old French poignal "dagger," literally "anything grasped with the fist," from poing "fist," from Latin pungus "fist," from PIE root *peuk- (see pugnacious). Probably altered in French by association with poindre "to stab." Cf. Latin pugnus "fist," pugio "dagger." As a verb from c.1600.
pons (n.): "bridge," in various Latin expressions, from Latin pons "bridge, connecting gallery, walkway," earlier probably "way, passage," from PIE *pent- "to go, tread" (see find (v.)). Especially pons asinorum "bridge of asses," nickname for the fifth proposition of the first book of Euclid, which beginners and slow wits find difficulty in "getting over": if two sides of a triangle are equal, the angles opposite these sides are also equal.
Pontiac: Ottawa tribal leader (c.1720-1769), his name is given in native (Algonquian) form as bwandiag. The city in Michigan, U.S., settled in 1818, was named for him as he is said to be buried nearby. The automobile brand was begun in 1926, discontinued 2010.
Pontic (adj.): 1550s; see Pontus + -ic.
pontifex (n.): member of the supreme college of priests in ancient Rome, 1570s, from Latin pontifex "high priest, chief of the priests," probably from pont-, stem of pons "bridge" (see pons) + -fex, -ficis, root of facere "make" (see factitious). If so, the word originally meant "bridge-maker," or "path-maker."

Weekley points out that, "bridge-building has always been regarded as a pious work of divine inspiration." Or the term may be metaphoric of bridging the earthly world and the realm of the gods. Other suggestions trace it to Oscan-Umbrian puntis "propitiary offering," or to a lost Etruscan word, in either case altered by folk etymology to resemble the Latin for "bridge-maker." In Old English, pontifex is glossed in the Durham Ritual (Old Northumbrian dialect) as brycgwyrcende "bridge-maker."
pontiff (n.): c.1600, "high priest," from French pontif (early 16c.), from Latin pontifex, title of a Roman high priest (see pontifex). Used for "bishop" in Church Latin, but not recorded in that sense in English until 1670s, specifically "the bishop of Rome," the pope. Pontifical, however, is used with this sense from mid-15c.
pontifical (adj.): early 15c., from Middle French pontifical and directly from Latin pontificalis "of or pertaining to the high priest," from pontifex (see pontifex). Hence pontificalia "trappings of a bishop."
pontificate (v.): 1818, "to act as a pontiff," from Medieval Latin pontificatus, past participle of pontificare "to be a pontifex," from Latin pontifex (see pontiff). Meaning "to assume pompous and dignified airs, issue dogmatic decrees" is from 1825. Meaning "to say (something) in a pontifical way" is from 1922. Related: Pontificated; pontificating.
pontificate (n.): 1580s, from Latin pontificatus "office of a pontiff," from pontifex (see pontifex).
pontification (n.): 1520s, "office of a bishop," noun of action from past participle stem of Medieval Latin pontificare (see pontificate (v.)). Meaning "something pontificated" is from 1925.
pontoon (n.): "flat-bottomed boat" (especially one to support a temporary bridge), 1670s, from French pontoon, from Old French ponton (14c.) "bridge, drawbridge, boat-bridge; flat-bottomed boat," from Latin pontonem (nominative ponto) "flat-bottomed boat," from pons "bridge" (see pons). Pontoon bridge is first recorded 1778.
Pontus: ancient district of Anatolia, from Greek pontos "sea" (see pons).
pony (n.): 1650s, powny, from Scottish, apparently from obsolete French poulenet "little foal" (mid-15c.), diminutive of Old French poulain "foal," from Late Latin pullanus "young of an animal," from Latin pullus "young of a horse, fowl, etc." (see foal (n.)) [Skeat's suggestion, still accepted].

German, sensibly, indicates this animal by attaching a diminutive suffix to its word for "horse," which might yield Modern English *horslet. Modern French poney is a 19c. borrowing from English. Meaning "crib of a text as a cheating aid" (1827) and "small liquor glass" (1849) both are from notion of "smallness" (the former also "something one rides"). As the name of a popular dance, it dates from 1963. The U.S. Pony Express began 1860 (and operated about 18 months before being superseded by the transcontinental telegraph). The figurative one-trick pony is 1897, American English, in reference to circus acts.
pony (v.): 1824, in pony up "to pay," of uncertain origin. OED says from pony (n.), but not exactly how. In other sources said to be from slang use of Latin legem pone to mean "money" (first recorded 16c.), because this was the title of the Psalm for March 25, a Quarter Day and the first payday of the year (the Psalm's first line is Legem pone michi domine viam iustificacionum "Teach me, O Lord, the ways of thy statutes").
ponytail (n.): long hair style, originally of girls, 1950, from pony (n.) + tail (n.).
Ponzi scheme: investment scam by which early investors are paid off from the contributions of later ones, 1957, in reference to Charles Ponzi (1882-1949), who perpetrated such a scam in U.S., 1919-20.
poo (n.): also pooh, baby-talk for "excrement," 1950s (cf. poop (n.2)).
pooch (n.): "dog," 1924, American English, of unknown origin.
poodle (n.): 1808, from German Pudel, shortened form of Pudelhund "water dog," from Low German Pudel "puddle" (cf. pudeln "to splash;" see puddle (n.)) + German Hund "hound" (see hound (n.)). Probably so called because the dog was used to hunt water fowl. Figurative sense of "lackey" (chiefly British) is attested from 1907. Poodle-faker, British army slang for "ingratiating male," is from 1902, likely euphemistic.
poof (n.2): "effeminate man, male homosexual," c.1850, perhaps a corruption of puff. The Australian extended form poofter is attested from 1910.
poof (n.1): sound of a puff of breath or air, 1824, imitative.
pooh: 1590s, "a 'vocal gesture' expressing the action of puffing anything away" [OED], first attested in Hamlet Act I, Scene III, where Polonius addresses Ophelia with, "Affection! pooh! you speak like a green girl, / Unsifted in such perilous circumstance. / Do you believe his tenders, as you call them?" But the "vocal gesture" is perhaps ancient.
pooh-bah (n.): "leader who maintains excessive bureaucratic control," 1888, from Pooh-Bah, the name of the "Lord High Everything Else" character in Gilbert and Sullivan's "The Mikado" (1885).
pooh-pooh (v.): "to dismiss lightly and contemptuously," 1827, a slang reduplication of dismissive expression pooh. Among the many 19th century theories of the origin of language was the Pooh-pooh theory (1860), which held that language grew from natural expressions of surprise, joy, pain, or grief.
pool (n.1): "small body of water," Old English pol "small body of water; deep, still place in a river," from West Germanic *pol- (cf. Old Frisian and Middle Low German pol, Dutch poel, Old High German pfuol, German Pfuhl). As a short form of swimming pool it is recorded from 1921. Pool party is from 1965.
pool (n.2): game similar to billiards, 1848, originally (1690s) a card game played for collective stakes (a "pool"), from French poule "stakes, booty, plunder," literally "hen," from Old French poille "hen, young fowl" (see foal (n.)).

Perhaps the original notion is from jeu de la poule, supposedly a game in which people threw things at a chicken and the player who hit it, won it, which speaks volumes about life in the Middle Ages. The notion behind the word, then, is "playing for money." The connection of "hen" and "stakes" is also present in Spanish polla and Walloon paie.

Meaning "collective stakes" in betting first recorded 1869; sense of "common reservoir of resources" is from 1917. Meaning "group of persons who share duties or skills" is from 1928. From 1938 as short for football pool in wagering. Pool shark is from 1898. The phrase dirty pool "underhanded or unsportsmanlike conduct," especially in politics (1951), seems to belong here now, but the phrase dirty pool of politics, with an image of pool (n.1) is recorded from 1871 and was in use early 20c.
pool (v.1): "to make a common interest, put things into a pool," 1871, from pool (n.2). Related: Pooled; pooling.
pool (v.2): of liquid, "to form a pool or pools," 1620s, from pool (n.1).
poontang (n.): "sex with a woman; woman regarded as a sex object; female genitalia," c.1910, of uncertain origin, probably via New Orleans Creole, from French putain "prostitute," from Old French pute "whore" (cognate with Spanish and Provençal puta), probably from fem. of Vulgar Latin *puttus "girl" (cf. Old Italian putta "girl"), from Latin putus (originally "pure, bright, splendid").

But also possibly from or influenced by Old French put, from Latin putidus "stinking" on notion of the "foulness" of harlotry [Buck], or for more literal reasons (among the 16c.-17c. slang terms for "whore" in English were polecat, which might also be a pun, and fling-stink). Shortened form poon is recorded from 1969.
poop (n.1): "stern deck of a ship," c.1400, from Middle French poupe "stern of a ship" (14c.), from Old Provençal or Italian poppa, from Latin puppis "poop, stern," of uncertain origin. Poop deck attested by 1779.
poop (n.2): "excrement," 1744, a children's euphemism, probably of imitative origin. The verb in this sense is from 1903. Cf. the same word in the sense "to break wind softly," attested from 1721, earlier "to make a short blast on a horn" (late 14c.). Meaning "stupid or dull person" is from 1915. Pooper-scooper attested from 1970.
poop (n.3): "up-to-date information," 1941, in poop sheet, U.S. Army slang, of unknown origin, perhaps from poop (n.2).
poop (v.): "become tired," 1931, of unknown origin (see pooped). Related: Pooping.
pooped (adj.): "tired," 1931, of unknown origin, perhaps imitative of the sound of heavy breathing from exhaustion (cf. poop (n.2)). But poop, poop out were used in 1920s in aviation, of an engine, "to die." Also there is a verb poop, of ships, "to be overwhelmed by a wave from behind," often with catastrophic consequences (see poop (n.1)); hence in figurative nautical use, "to be overcome and defeated" (attested in 1920s).
It is an easy thing to "run"; the difficulty is to know when to stop. There is always the possibility of being "pooped," which simply means being overtaken by a mountain of water and crushed into the depths out of harm's way for good and all. [Ralph Stock, "The Cruise of the Dream Ship," 1921]
poor (adj.): c.1200, "lacking money or resources, destitute; needy, indigent; small, scanty," from Old French povre "poor, wretched, dispossessed; inadequate; weak, thin" (Modern French pauvre), from Latin pauper "poor, not wealthy," from pre-Latin *pau-paros "producing little; getting little," a compound from the roots of paucus "little" (see paucity) and parare "to produce, bring forth" (see pare).

Replaced Old English earm. Figuratively from early 14c. Meaning "of inferior quality" is from c.1300. Of inhabited places from c.1300; of soil, etc., from late 14c. The poor boy sandwich, made of simple but filling ingredients, was invented and named in New Orleans in 1921. To poor mouth "deny one's advantages" is from 1965 (to make a poor mouth "whine" is Scottish dialect from 1822). Slang poor man's ________ "the cheaper alternative to _______," is from 1854.
poor (n.): "poor persons collectively," mid-12c., from poor (adj.). The Latin adjective pauper "poor" also was used in a noun sense "a poor man."
poorhouse (n.): 1781, from poor (n.) + house (n.).
poorly (adv.): early 13c., "inadequately, badly, insufficiently," from poor (adj.) + -ly (2). Meaning "in ill health" is from 1750.
poorness (n.): late 13c., from poor (adj.) + -ness.
pop (n.1): "a hit with an explosive sound," c.1400, of imitative origin. Meaning "flavored carbonated beverage" is from 1812.
A new manufactory of a nectar, between soda-water and ginger-beer, and called pop, because 'pop goes the cork' when it is drawn. [Southey, letter, 1812]
Sense of "ice cream on a stick" is from 1923 (see popsicle). Meaning "the (brief) time of a 'pop'" is from 1530s. Pop goes the weasel, a country dance, was popular 1850s in school yards, with organ grinders, at court balls, etc.
pop (adj.): "having popular appeal," 1926, of individual songs from many genres; 1954 as a noun, as genre of its own; abbreviation of popular; earlier as a shortened form of popular concert (1862), and often in the plural form pops. Pop art first recorded 1957, said to have been in use conversationally among Independent group of artists from late 1954. Pop culture attested from 1959, short for popular culture (attested by 1846).