Online Etymology Dictionary

-path: suffix used in modern formations to mean "one suffering from" (a disease or condition), also "one versed in" (a certain type of treatment), from Gk. -pathes, from pathos "suffering" (see pathos).
-phagous: comb. form meaning "eating, feeding on," from Gk. -phagos "eater of," from phagein "to eat," lit. "to have a share of food," from PIE base *bhag- "to share out, apportion, distribute," also "to get a share" (cf. Skt. bhajati "assigns, allots, apportions, enjoys, loves," bhagah "allotter, distributor, master, lord," bhaksati "eats, drinks, enjoys;" Pers. bakhshidan "to give;" O.C.S. bogatu "rich").
-phane: comb. form meaning "having the appearance of," from Gk. -phanes, from phainein "to show," phainesthai "to appear" (see phantasm).
-phemia: comb. form meaning "speech," from Gk. -phemia, from pheme "speech," from stem of phemi "I speak," cognate with L. fari "to speak," fama "report, reputation" (see fame).
-phile: via Fr. and L. from Gk. -philos, common suffix in personal names, from philos "loving, dear," from philein "to love," of unknown origin.
-philia: comb. form meaning "friendship, fondness," from Gk. philia "affection," from philos "loving."
-phobe: comb. form meaning "fearing," from Fr. -phobe, from L. -phobus, from Gk. -phobos "fearing," from phobos "fear, panic, flight," phobein "put to flight, frighten" (see phobia).
-phone: comb. form meaning "voice," from Gk. phone "voice, sound," from PIE base *bha- "to speak, say, tell" (cf. L. for, fari "to speak," fama "talk, report;" see fame).
-plasia: comb. form denoting "formation," Mod.L., from Gk. plasis "molding, formation," from plassein "to mold" (see plasma).
-plast: comb. form denoting "something made," from Gk. plastos "formed, molded," from plassein "to mold" (see plasma).
-plasty: comb. form meaning "act or process of forming, plastic surgery," from Gk. -plastia, from plastos "molded, formed" (see plaster).
P: a rare letter in the initial position in Gmc., in part because by Grimm's Law PIE p- became Gmc. f-; even with early L. borrowings, -p- takes up only a little over 4 pages in J.R. Clark Hall's "Concise Anglo-Saxon Dictionary," compared to 31 pages for B and more than 36 for F. But it now is the third most common initial letter in the Eng. vocabulary, and with C and S, comprises nearly a third of the words in the dictionary, a testimonial to the flood of words that have entered the language since 1066 from L., Gk., and Fr. To mind one's Ps and Qs (1779), possibly is from confusion of these letters among children learning to write. Another theory traces it to old-time tavern-keepers tracking their patrons' bar tabs in pints and quarts. But cf. also to be P and Q (1612), "to be excellent," a slang phrase said to derive from prime quality.
P.C.: abbreviation for personal computer is from 1978; abbreviation for politically correct is by 1990.
P.C.P.: 1960s, from animal tranquilizer phencyclidine.
P.D.Q.: acronym for pretty damn quick, attested from 1875.
p.m.: abbreviation of L. post meridiem "after noon" (1647).
P.O.W.: acronym for prisoner of war, coined 1919, but not common until World War II.
P.S.: 1616, abbreviation of L. post scriptum (see postscript).
pa: 1811, colloquial shortening of papa (q.v.).
Pablum: See pabulum.
pabulum: "food," 1678, from L. pabulum "fodder, food," from PIE base *pa- "to protect, feed" (see food) + instrumentive suffix *-dhlom. Pablum (1932), derived from this, is a trademark (Mead Johnson & Co.) for a soft, bland cereal used as a food for weak and invalid people, hence fig. use (attested from 1970, first by U.S. Vice President Spiro Agnew) in ref. to "mushy" political prose.
paca: Central and South American rodent, 1657, from Sp., from Tupi (Brazil) paca.
pace (1): "a step," late 13c., from O.Fr. pas, from L. passus "a step," lit. pp. of pandere "to stretch (the leg), spread out," from PIE *pat-no-, from base *pete- "to spread" (cf. Gk. petalon "a leaf," O.E. fæðm "embrace, bosom, fathom"). The verb is first attested 1510s, from the noun. Also, "a measure of five feet" [Johnson]. Pace-setter in fashion is from 1895.
pace (2): "with the leave of," 1863, from L. pace, abl. of pax "peace," as in pace tua "with all deference to you;" from PIE *pak- "to fasten" (see pax).
pacemaker: also pace-maker, 1884, originally a rider or boat that sets the pace for others in training; sense of "man-made device for stimulating and regulating heartbeat" is from 1951.
pachinko: 1953, from Japanese, "pinball machine," also "slingshot, handgun," from pachin, of echoic origin, + dim. suffix -ko.
pachyderm: 1838, from Fr. pachyderme (c.1600), adopted as a biological term 1797 by Fr. naturalist Georges Léopole Chrétien Frédéric Dagobert, Baron Cuvier (1769-1832), from Gk. pachydermos "thick-skinned," from pachys "thick" (from PIE *bhengh-, cf. Skt. bahu- "much") + derma "skin."
pachysandra: 1813, from Mod.L. (1803), from Gk. packhys "thick" + aner (gen. andros) "man" (see anthropo-), used in botany to mean "having stamens."
pacific: 1540s, "tending to make peace," from M.Fr. pacifique, from L. pacificus "peaceful, peace-making," from pax (gen. pacis) "peace" + root of facere "to make" (see factitious). Meaning "peaceful, calm" is first recorded 1630s. Related: Pacifically.
Pacific Ocean: 1660, from M.L. Pacificum, neut. of L. pacificus (see pacific); so called c.1500 by Magellan when he sailed into it and found it calmer than the stormy Atlantic.
pacifier: "one who pacifies or appeases," 1530s; see pacify. The meaning "nipple-shaped device for babies" is first recorded 1904.
pacifism: 1902, from Fr. pacifisme, from pacifique (see pacific).
pacifist: 1906, from Fr. pacifiste (see pacifism). Won out over pacificist (1907). Related: Pacifistic.
pacify: mid-15c., from M.Fr. pacifier, from O.Fr., "make peace," from L. pacificare "to make peace, pacify," from pacificus (see pacific).
pack (n.): "bundle," early 13c., probably from a Low Ger. word (cf. M.Du. pac, pack "bundle," M.L.G. pak, M.Flem. pac, attested from 1199), originally a term of wool traders in Flanders; or possibly from O.N. pakki, all of unknown origin. Italian pacco is a Du. loan word. Meaning "set of persons" (usually of a low character" is c.1300, older than sense of "group of hunting animals" (early 15c.). Extended to collective sets of playing cards (1590s), floating ice (1791), cigarettes (1924), and submarines (1943). Meaning "knapsack on a frame" is attested from 1916. Pack-horse is from late 15c.; packsaddle "saddle for supporting packs on the back of a mount" is from late 14c. (pakke sadil). Pack of lies first attested 1763.
pack (v.): c.1300, "to put together in a pack," from pack (n.), possibly influenced by Anglo-Fr. empaker (1294) and M.L. paccare "pack." Some senses suggesting "make secret arrangement" are from an Elizabethan mispronunciation of pact. Sense of "to carry or convey in a pack" (1805) led to general sense of "to carry in any manner;" hence to pack heat "carry a gun," underworld slang from 1940s; "to be capable of delivering" (a punch, etc.) is from 1921.
pack-rat: common name for the N.Amer. bushytailed woodrat (Neotoma cinerea) is attested from 1885, from pack (v.), from the rodent's habit of dragging objects off to their holes. Used figuratively or allusively of persons who won't discard anything from c.1850, which means either the rat's name is older than that or the human sense is the original one.
package: 1540, "the act of packing," from pack (n.) or from cognate Du. pakkage "baggage." The main modern sense of "bundle, parcel" is first attested 1722. The verb is 1922, from the noun. Package deal is from 1952.
packet: 1530, from M.E. pak "bundle" (see pack (n.)) + dim. suffix -et; perhaps modified on Anglo-Fr. pacquet (M.Fr. pacquet), which is ult. a dim. of M.Du. pak. A packet boat (1641) was originally one that carried mails.
pact: early 15c., from M.Fr. pacte "agreement, treaty, compact," from L. pactum "contract, covenant," from neut. pp. of pacisci "to covenant, to agree, make a treaty," from PIE base *pag- "fix, join together, unite, make firm" (cf. Skt. pasa- "cord, rope," Avestan pas- "to fetter," Gk. pegnynai "to fix, make firm, fast or solid," L. pangere "to fix, to fasten," Rus. pazu "joint," O.E. fegan "to join," fon "to catch seize").
pad (n.): 1554, "bundle of straw to lie on," possibly from Low Ger. or Flem. pad "sole of the foot." Meaning "cushion-like part of an animal foot" is from 1836 in Eng. Generalized sense of "something soft" is from c.1700; the sense of "a number of sheets fastened together" (in writing pad, drawing pad, etc.) is from 1865. Sense of "take off or landing place for a helicopter" is from 1960. The word persisted in underworld slang from early 18c. in the sense "sleeping place," and was popularized again c.1959, originally in beatnik speech (later hippie slang) in its original sense of "place to sleep temporarily." The verb meaning "to stuff, increase the amount of" is first recorded 1827, from the noun; transf. to expense accounts, etc. from 1913. Padded cell in an asylum or prison is from 1862 (padded room).
pad (v.): "to walk," 1553, probably from M.Du. paden "walk along a path, make a path," from pad, pat "path." Originally criminals' slang, perhaps of imitative origin (sound of feet trudging on a dirt road).
paddle (n.): 1407, padell "small spade," from M.L. padela, perhaps from L. patella "pan, plate," dim. of patina. Meaning "short oar with a wide blade" is from 1624. As an instrument used for beating clothes (and slaves, and schoolboys), it is recorded from 1828, Amer.Eng.; the verb meaning "to beat with a paddle, spank" is first recorded 1856. Paddlewheel is from 1805.
paddle (v.): "to dabble, wade in water," 1530, probably cognate with Low Ger. paddeln "tramp about," freq. of padjen "to tramp, to run in short steps," from pad (v.). Meaning "to move in water by means of paddles" (1677) is a different word, from paddle (n.).
paddock (1): "a frog, a toad," c.1300, dim. of pad "toad," from O.N. padda; common Gmc. (cf. Swed. padda, Dan. padde, O.Fris., M.Du. padde "frog, toad," also Du. schildpad "tortoise"), of unknown origin and with no certain cognates outside Gmc.
paddock (2): "an enclosure," 1622, alteration of M.E. parrock, from O.E. pearroc "enclosed space, fence" (see park). Or possibly from M.L. parricus (8c.), which is ult. from Gmc.
paddy (1): "rice field," 1623, "rice plant," from Malay padi "rice in the straw;" meaning "ground where rice is growing" (1948) is a shortening of paddy field.
Paddy (2): "Irishman," 1780, slang, from the pet form of the common Irish proper name Patrick (Ir. Padraig). It was in use in black slang by 1946 for any "white person." Paddy wagon is 1930, perhaps so called because many police officers were Irish. Paddywhack (1881) originally meant "an Irishman."
padlock: "removable lock," 1479, from lokke (see lock), but the first element is a complete mystery. The verb is attested from 1645.
padre: "priest, chaplain," 1584, from It., Sp. or Port. padre, from L. patrem (nom. pater) "father." The title of the regular clergy in those languages. Papar was the name the Norse gave to Irish monks whom they found in Iceland when they arrived.