Online Etymology Dictionary

pedo-: from Gk. pedo-, comb. form of pais "boy, child," from PIE base *peu- "small, little, few, young" (see few (adj.)). The British form paed- is better because it avoids confusion with ped-.
pedology: 1924, from Gk. pedon “ground, earth,” from PIE base *ped- (see foot).
pedometer: instrument for measuring distances covered by a walker, 1723, from Fr. pédomètre (1723), a hybrid coined from L. pedis (gen. of pes "foot") + Gk. metron (see meter (2)). At first Anglicized as waywiser.
pedophile: 1951, derived noun from pedophilia.
pedophilia: 1905, from Gk. pais (gen. paidos) "child" (see pedo-) + philos "loving." First attested in Havelock Ellis.
peduncle: 1753, from Mod.L. pedunculus “footstalk,” dim. of pes (gen. pedis) “foot” (see foot).
pedunculated: 1752, from Mod.L. pedunculatus, from pedunculus (see peduncle).
pee: 1788, "to urinate," euphemistic abbreviation of piss. Noun meaning "act of urination" is attested from 1902. Reduplicated form pee-pee is attested from 1923.
peek (v.): late 14c., piken "look quickly and slyly," of unknown origin. The words peek, keek, and peep all were used with more or less the same meaning 14c.-15c.; perhaps the ultimate source was M.Du. kieken. Related: Peeked; peeking. The noun meaning "a peek, glance" is attested from 1844.
peekaboo: also peek-a-boo, as a children's game attested from 1590s; as an adj. meaning "see-through" it dates from 1895. From peek (v.) + boo.
peel (v.): "to strip off," developed from O.E. pilian "to peel," and O.Fr. pillier, both from L. pilare "to strip of hair," from pilus "hair." Probably also influenced by L. pellis "skin, hide." The noun is 1580s, from earlier pill, pile (late 14c.), from the verb.
peel out: hot-rodders' slang, 1952, perhaps from peel "blade or wash of an oar" (1875, Amer.Eng.), earlier "shovel-shaped instrument" used by bakers, etc. (c.1400), from O.Fr. pele, from L. pala "spade, shovel," of unknown origin. Or it may be from aircraft pilot phrase peel away "veer away from formation" (WWII), or from earlier Amer.Eng. slang peel it "run away at full speed" (1860).
peeler: "policeman," 1817, British colloquial, originally a member of the Irish constabulary, named for Sir (at that time Mr.) Robert Peel (1788-1850) who founded the Irish Constabulary (cf. bobby). Meaning "strip-tease artist" (1951) is from peel (v.).
peen: 1680s, "sharp or thin end of a hammer head, opposite the face," probably from a Scandinavian source (cf. Norw. dialectal penn "peen," O.Swed. pæna "beat iron thin with a hammer"). Earlier as a verb, "to beat thin with a hammer" (1510s).
peep (1): "glance" (esp. through a small opening), mid-15c., perhaps alteration of M.E. piken (see peek). The noun was first in sense found in peep of day (1520s); meaning "a furtive glance" is first recorded 1730. Peep-hole is from 1680s; peep-show is from 1851 (not typically salacious until c.1914). Slang peeper "eye" is from c.1700. Peeping Tom "a curious prying fellow" is from 1796; connection with Lady Godiva story dates only from 1837.
peep (2): "make a short chirp," c.1400, probably altered from pipen (mid-13c.), ultimately imitative (cf. L. pipare, Fr. pepier, Ger. piepen, Lith. pypti, Czech pipati, Gk. pipos). The noun is attested from early 15c.; meaning "slightest sound or utterance" (usually in a negative context) is attested from 1903. Peeper "tree frog" is first recorded 1857, Amer.Eng.
peepee: 1923, childish reduplication of pee.
peer (n.): c.1300, "an equal in civil standing or rank" (early 13c. in Anglo-Latin), from Anglo-Fr. peir, O.Fr. per (10c.), from L. par "equal." Sense of "noble" (late 14c.) is from Charlemagne's Twelve Peers in the old romances, like knights of the Round Table, originally so called because all were equal. Sociological sense of "one of the same age group or social set" is from 1944. Peer review attested by 1970. Peer pressure is first recorded 1971.
peer (v.): 1590s, variant of piren (late 14c.), with a long -i-, probably related to or from E. Fris. piren "to look," of uncertain origin. Influenced in form and sense by M.E. peren (late 14c.), aphetic form of aperen (see appear). Related: Peered; peering.
peerage: mid-15c., from peer (n.) + -age.
peerless: early 14c., from peer (n.) + -less.
peeve (v.): 1908, back formation from peevish. As a noun, attested by 1911. Related: Peeved; peeves.
peevish: late 14c., peyvesshe "perverse, capricious, silly," of uncertain origin, possibly modeled on L. perversus "reversed, perverse," pp. of pervertere "to turn about" (see pervert). Meaning "cross, fretful" first recorded 1520s.
peewee (adj.): 1877, "small, tiny, for children," a dialect word, possibly a varied reduplication of wee. Attested earlier (1848) as a noun meaning "a small marble." (Baseball Hall-of-Famer Harold "Peewee" Reese got his nickname because he was a marbles champion before he became a Dodgers shortstop.) As a type of bird (variously applied on different continents) it is attested from 1886, imitative of a bird cry.
peg (n.): mid-15c., from M.Du. pegge "peg," a common Low Ger. word of uncertain origin (cf. Low Ger. pigge "peg," M.Du. pegel "little knob used as a mark"). The verb meaning "fasten with or as if on a peg" is first recorded 1590s, from the noun. Slang sense of "identify, classify" first recorded 1920. Related: Pegged; pegging. To be a square peg in a round hole "be inappropriate for one's situation" is attested from 1836; to take someone down a peg is from 1580s, but the original lit. sense is uncertain (most of the likely candidates are not attested until centuries later).
Pegasus: winged horse in Gk. mythology, late 14c., from L., from Gk. Pegasos, usually said to be from pege "spring, font" (pl. pegai), especially in "springs of Ocean," near which Medusa was said to have been killed by Perseus (Pegasus sprang from her blood). But this may be folk etymology, and the suffix -asos suggests a pre-Gk. origin.
pegomancy: "divination by fountains," 1727, from Gk., from pege "fountain, spring" (of unknown origin) + manteia "oracle, divination" (see -mancy).
peignoir: 1835, "lady's loose robe," from Fr. peignoir, from M.Fr. peignouoir "garment worn over the shoulders while combing the hair" (16c.), from peigner "to comb," from L. pectinare, from pecten (gen. pectinis) "a comb," related to pectere "to comb." A gown put on while coming from the bath; misapplied in English to a woman's morning gown.
Peirce: surname, attested from late 12c., from O.Fr. Piers, nom. of proper name Pierre.
pejoration: 1650s, from M.L. pejorationem, noun of action from pejorare (see pejorative).
pejorative: "depreciative, disparaging," 1882, from Fr. péjoratif (fem. péjorative), from L.L. pejoratus, pp. of pejorare "make worse," from L. pejor "worse," related to pessimus "worst," pessum "downward, to the ground." English had a verb pejorate "to worsen" from 1640s.
Pekingese: 1907, "small long-haired dog of the pug type," so called because originally brought from the Imperial Palace at Peking, China.
pelage: from Fr. pelage, from O.Fr. pel “hair,” from L. pilus “hair” (see pile (3)).
Pelagian: 1530s, from M.L. Pelagianus, from Pelagius, Latinized form of the name of 4c. British monk who denied the doctrine of original sin. Combated by Augustine, condemned by Pope Zosimus in 418 C.E. His name in Welsh was Morgan, lit. "sea-dweller" (cf. Gk. pelagos "sea").
pelagic: "pertaining to the sea," 1650s, from L. pelagicus, from Gk. pelagikos, from pelagos "sea," from PIE *p(e)lag- "to spread out" (cf. Gk. plagos "side," L. plaga "hunting net, curtain, region"), from base *pele- "spread out, flat" (see plane (1)).
Pelasgian: late 15c., "of the Pelasgi," from L. Pelasgius, from Gk. Pelasgios "of the Pelasgi," from Pelasgoi "the Pelasgi," name of a prehistoric people of Greece and Asia Minor who occupied Greece before the Hellenes, probably originally *Pelag-skoi, lit. "Sea-people" (see pelagic).
pelf: late 14c., from Anglo-Fr. pelf, from O.Fr. pelfre "booty, spoils" (11c.), of unknown origin, related to pilfer (q.v.). Meaning "money, riches," with a pejorative overtone first recorded c.1500.
pelican: O.E. pellicane, from L.L. pelecanus, from Gk. pelekan "pelican" (so used by Aristotle), apparently related to pelekas "woodpecker" and pelekys "ax," perhaps so called from the shape of the bird's bill. Used in Septuagint to translate Heb. qaath. The fancy that it feeds its young on its own blood is an Egyptian tradition properly belonging to some other bird.
pell: “a parchment,” mid-15c., earlier “skin, hide” (14c.), from Anglo-Fr. pell, from O.Fr. pel (13c., Mod.Fr. peau), from L. pellem, pellis “skin, leather, parchment, hide” (see film).
pell-mell (adv.): "confusedly," 1579, from M.Fr. pêle-mêle, from O.Fr. pesle mesle (12c.), apparently a jingling rhyme on the second element, which is from the stem of the verb mesler "to mix, mingle."
pellagra: chronic disease caused by dietary deficiency and characterized by skin eruptions, 1811, a hybrid formed from L. pellis "skin" (see film) + Gk. agra "a catching, seizure."
pellet: mid-14c., from O.Fr. pelote "small ball" (11c.), from V.L. *pilotta, dim. of L. pila "ball," perhaps originally "ball of hair," from pilus "hair."
pellicle: 1540s, from L. pellicula “small or thin skin,” dim. of pellis “skin, leather, parchment, hide” (see film).
pellucid: "transparent, translucent," 1619, from L. pellucidus "transparent," from pellucere "shine through," from per- "through" + lucere "to shine" (see light (n.)).
Peloponnesus: peninsula of southern Greece, late 15c., from L., from Gk. Peloponnesos, second element apparently nesos "island," first element said to be named for Pelops, son of Tantalus, who killed him and served him to the gods as food (they later restored him to life). The proper name is probably from pellos "dark" + ops "face, eye." But the association with the peninsula name likely is folk etymology.
peloton: 1706, “small body of soldiers, platoon,” from Fr. peleton, derivative of pelote “ball, heap, platoon” (11c.); see platoon.
pelt (v.): "to strike" (with something), c.1500, perhaps from an unrecorded O.E. *pyltan, from M.L. *pultiare, from L. pultare "to beat." Or from O.Fr. peloter "to strike with a ball," from pelote "ball" (see pellet). Related: Pelted; pelting.
pelt (n.): "skin of a fur-bearing animal," early 15c., related to earlier pel (c.1300), contraction of pelet, from O.Fr. pelete "fine skin, membrane," dim. of pel "skin," from L. pellis "skin, hide" (see film).
pelvic: 1839, irregularly formed from pelvis + -ic. OED prefers “the better-formed” Fr. pelvien.
pelvis: 1610s, "basin-like cavity formed by the bones of the pelvic girdle," from Mod.L., from L. pelvis "basin, laver," Old L. peluis "basin," from PIE *pel- "container" (cf. Skt. palavi "vessel," Gk. pelex "helmet," pelike "goblet, bowl," O.N., O.E. full "cup").