Online Etymology Dictionary

polystyrene (n.): 1922, so called because it is a polymer of styrene.
polysyllabic (adj.): 1650s (implied in polysyllabical), from Medieval Latin polysyllabicus, from Greek polysyllabikos; see poly- + syllabic.
polysyllable (n.): 1560s; see poly- + syllable. As a rule, a word of more than three syllables.
polysynthesis (n.): 1837, from poly- + synthesis.
polytechnic (adj.): 1805, "pertaining to instruction in many (technical) subjects," from French École Polytechnique, engineering school founded 1794 (as École des Travaux publics) in Paris; from Greek polytekhnos "skilled in many arts," from polys "many" (see poly-) + tekhne "art" (see techno-). As a noun (short for polytechnic institution) from 1836.
polytheism (n.): 1610s, from French polythéisme (16c.), formed from Greek polytheia "polytheism," polytheos "of many gods," from polys "many" (see poly-) + theos "god" (see theo-).
polytheist (n.): 1610s; see polytheism + -ist.
polyunsaturated (adj.): 1921, from poly- + unsaturated.
polyurethane (n.): 1944, from polymer + urethane.
polyvalent (adj.): 1881, from poly- + -valent, from Latin valentem, present participle of valere "be worth" (see valiant). Coined by German chemist Emil Erlenmeyer (1825-1909), who also designed the flask that bears his name.
polyvinyl (n.): 1930, polymer of vinyl chloride. In chemistry, vinyl was used from 1863 as the name of a univalent radical derived from ethylene, from Latin vinum "wine" (see wine (n.)), because ethyl alcohol is the ordinary alcohol present in wine.
pom-pom (n.): "Maxim automatic gun," 1899, of imitative origin, soldiers' slang from the Boer War. For the ornamental tuft, see pompom.
pomace (n.): 1570s, "crushed pulp of apples," from Old French pomaz, plural of pome "cider; apple," from Latin pomum "fruit; apple" (see Pomona).
pomaceous (adj.): 1706, from Vulgar Latin *poma "apple," originally plural of Latin pomus "fruit," later "apple" (see Pomona) + -aceous.
pomade (n.): 1560s, from Middle French pommade "an ointment" (16c.), from Italian pomata, from pomo "apple," from Latin pomum "fruit; apple" (see Pomona). So called because the original ointment recipe contained mashed apples.
pome (n.): late 14c., of types of apples or apple-shaped objects, from Old French pome "apple" (12c., Modern French pomme), from Late Latin or Vulgar Latin *poma "apple," originally plural of Latin pomus "fruit," later "apple" (see Pomona).
pomegranate (n.): c. 1300, poumgarnet (a metathesized form), from Old French pome grenate (Modern French grenade) and directly from Medieval Latin pomum granatum, literally "apple with many seeds," from pome "apple; fruit" (see Pomona) + grenate "having grains," from Latin granata, fem. of granatus, from granum "grain" (see grain). The classical Latin name was malum granatum "seeded apple." Italian form is granata, Spanish is granada. The -gra- spelling restored in English early 15c.
pomelo (n.): 1858, of uncertain origin; apparently related to Latin pomum "fruit; apple" (see Pomona).
Pomerania (n.): region and former province of Prussia on the Baltic coast of modern Poland (German Pommern, Polish Pomorze), Medieval Latin, from Pomerani, name of a Slavic tribe there, from Polish po morze "by the sea."
Pomeranian (n.): type of dog, 1760, from Pomerania, former province of Prussia on the south coast of the Baltic Sea.
pommel (n.): mid-13c., "ornamental knob;" c. 1300, "knob at the end of a sword hilt," from Old French pomel (12c., Modern French pommeau), "rounded knob," diminutive of pom "hilt of a sword," from Late Latin pomellum, diminutive of Latin pomum "apple" (see Pomona), the connecting notion being "roundness." Sense of "front peak of a saddle" first recorded mid-15c. In Middle English poetry it also sometimes meant a woman's breast. The gymnast's pommel horse is attested from 1908.
pommes frites (n.): "fried potatoes," 1872, French, from pomme "potato" (see pome).
Pomona (n.): Roman goddess of fruit, from Latin pomum "apple; fruit," of uncertain origin. "Possibly from *po-emo- 'taken off, picked'; *po-omo- or *pe-omo- are also conceivable" [de Vaan]. Or perhaps borrowed from a lost Mediterranean language.
pomp (n.): c. 1300, from Old French pompe "pomp, magnificence" (13c.) and directly from Latin pompa "procession, pomp," from Greek pompe "solemn procession, display," literally "a sending," from pempein "to send." In Church Latin, used in deprecatory sense for "worldly display, vain show."
pompadour (n.): 1887 as a men's hairstyle; 1899 as a woman's style with the hair swept up over the forehead, in recognition of Jeanne-Antionette Poisson, Marquise de Pompadour (1721-1764), mistress of Louis XV from 1745-50, who wore her hair in an upswept style. Used in her lifetime in reference to various fashions, accessories, colors, furniture, etc. The estate of Pompadour is in the Limousin region.
pompano (n.): ocean fish, 1778, from American Spanish pampano, a name given to various types of fish, from Spanish, originally "vine, tendril," from Latin pampinus "tendril or leaf of a vine."
Pompeii: Roman town buried by volcanic eruption 79 C.E., excavated beginning in 1755; the name is from Oscan pompe "five," in reference to its five districts. Related: Pompeian.
pompier (n.): "fireman's scaling ladder," French, literally "fireman," from pompe "pump" (see pump (n.)).
pompom (n.): "ornamental round tuft" (originally on a hat, etc.), 1748, alteration of pompon "ornamental tuft; tuft-like flower head," from French pompon (1725), of unknown origin; perhaps related to Old French pompe "pomp."
pomposity (n.): early 15c., "pomp, solemnity," from Medieval Latin pompositas, from Late Latin pomposus "stately, pompous" (see pompous). The sense of "ostentatious display" is from 1610s; earlier in French pomposité.
pompous (adj.): late 14c., "characterized by exaggerated self-importance," from Old French pompos (14c., Modern French pompeux) and directly from Late Latin pomposus "stately, pompous," from Latin pompa "pomp" (see pomp). More literal (but less common) meaning "characterized by pomp" is attested from early 15c. Related: Pompously.
pon (prep.): also 'pon, 1550s, shortened form of upon.
ponce (n.): slang term, chiefly British, 1872, originally "a pimp, a man supported by women" (pouncey in same sense is attested from 1861), of unknown origin, perhaps from French pensionnaire "boarder, lodger, person living without working." Meaning "male homosexual" first attested 1932 in Auden [OED]. Also as a verb. Related: Poncey.
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. Pond scum (Spirogyra) is from 1864 (also called frog-spittle and brook-silk. As figurative for "someone extremely repulsive," from 1984.
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) "weight" (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." Compare 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 also are 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.