Online Etymology Dictionary

pedo-: before vowels ped-, word-forming element meaning "boy, child," from Greek pedo-, comb. form of pais "boy, child," especially a son, from PIE root *peu- "small, little, few, young" (see few (adj.)). The British form paed- is better because it avoids confusion with ped-.
pedology (n.): "scientific study of the soil," 1924, from Greek pedon "ground, earth," from PIE root *ped- (1) "foot" (see foot (n.)) + -logy. Related: Pedological. Earlier it was a word for "the study of children" (1894), from pedo-.
pedometer (n.): instrument for measuring distances covered by a walker, 1723, from French pédomètre (1712), a hybrid coined from Latin pedis (genitive of pes "foot;" see foot (n.)) + Greek metron "a measure" (see meter (n.2)). At first Englished as waywiser.
pedophile (n.): 1951, derived noun from pedophilia.
pedophilia (n.): 1900, from Greek pais (genitive paidos) "child" (see pedo-) + philos "loving" see -phile). First attested in an abstract of a report by Krafft-Ebing.
pedophiliac (adj.): 1951, from pedophilia.
pedophilic (adj.): 1920, from pedophilia + -ic.
peduncle (n.): 1753, from Modern Latin pedunculus "footstalk," diminutive of pes (genitive pedis) "foot," from PIE root *ped- (1) "a foot" (see foot (n.)).
pedunculated (adj.): 1752, from Modern Latin pedunculatus, from pedunculus (see peduncle).
pee (v.): 1788, "to spray with urine," euphemistic abbreviation of piss. Meaning "to urinate" is from 1879. Related: Peed; peeing. Noun meaning "act of urination" is attested from 1902; as "urine" from 1961. 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 Middle Dutch kieken. Related: Peeked; peeking.
peek (n.): "a peek, glance," 1844, from peek (v.).
peekaboo (n.): also peek-a-boo, as a children's game attested from 1590s; as an adjective meaning "see-through, open," it dates from 1895. From peek (v.) + boo.
peel (v.): "to strip off," developed from Old English pilian "to peel, skin, decorticate, strip the skin or ring," and Old French pillier, both from Latin pilare "to strip of hair," from pilus "hair" (see pile (n.3)). Probably also influenced by Latin pellis "skin, hide." Related: Peeled; peeling. Figurative expression keep (one's) eyes peeled be observant, be on the alert" is from 1853, American English.
peel (n.1): piece of rind or skin, 1580s, from earlier pill, pile (late 14c.), from peel (v.)).
peel (n.2): "shovel-shaped instrument" used by bakers, etc., c. 1400, from Old French pele (Modern French pelle) "shovel," from Latin pala "spade, shovel, baker's peel," of unknown origin.
peel out (v.): hot-rodders' slang, 1952, perhaps from peel "blade or wash of an oar" (1875, American English), earlier "shovel-shaped instrument" (see peel (n.2). Or it might be from aircraft pilot phrase peel off "veer away from formation" (World War II), or from earlier American English slang peel it "run away at full speed" (1860).
peeler (n.): "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 (compare bobby). In Middle English it meant "robber, thief" (mid-14c.). Meaning "strip-tease artist" (1951) is from peel (v.) in colloquial sense of "strip off clothing" (1820).
peen (n.): 1680s, "sharp or thin end of a hammer head, opposite the face," probably from a Scandinavian source (compare Norwegian dialectal penn "peen," Old Swedish pæna "beat iron thin with a hammer"). Earlier as a verb, "to beat thin with a hammer" (1510s).
peep (v.1): "glance" (especially through a small opening), mid-15c., perhaps alteration of Middle English piken (see peek (v.)). Peeping Tom "a curious prying fellow" [Grose] is from 1796 (see Godiva).
peep (v.2): "make a short chirp," c. 1400, probably altered from pipen (mid-13c.), ultimately imitative (compare Latin pipare, French pepier, German piepen, Lithuanian pypti, Czech pipati, Greek pipos).
peep (n.1): 1520s, first in sense found in peep of day, from peep (v.1); meaning "a furtive glance" is first recorded 1730.
peep (n.2): "short chirp," early 15c., from peep (v.2); meaning "slightest sound or utterance" (usually in a negative context) is attested from 1903. Meaning "young chicken" is from 1680s. The marshmallow peeps confection are said to date from 1950s.
peep-hole (n.): 1680s, from peep (v.1) + hole (n.).
peep-show (n.): 1851 (not typically salacious until c. 1914), from peep (v.1) + show (n.).
peepee: 1923, childish reduplication of pee.
peeper (n.): 1650s, "one who peeps," agent noun from peep (v.1). Slang meaning "eye" is c. 1700. From 1590s as "young chicken" and 1857 as "tree frog" (American English), both from peep (v.2).
peer (n.): c. 1300, "an equal in rank or status" (early 13c. in Anglo-Latin), from Anglo-French peir, Old French per (10c.), from Latin par "equal" (see par (n.)). Sense of "a noble" (late 14c.) is from Charlemagne's Twelve Peers in the old romances, who, like the Arthurian knights of the Round Table, originally were 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.): "to look closely," 1590s, variant of piren (late 14c.), with a long -i-, probably related to or from East Frisian piren "to look," of uncertain origin. Influenced in form and sense by Middle English peren (late 14c.), shortened form of aperen (see appear). Related: Peered; peering.
peerage (n.): mid-15c., "peers collectively," from peer (n.) + -age. Probably on model of Old French parage.
peerless (adj.): c. 1300, from peer (n.) + -less.
peeve (v.): 1907 (implied in peeved), back-formation from peevish. As a noun, attested by 1910. Related: Peeved; peeving; peeves.
peevish (adj.): late 14c., peyvesshe "perverse, capricious, silly," of uncertain origin, possibly modeled on Latin perversus "reversed, perverse," past participle of pervertere "to turn about" (see pervert (v.)). Meaning "cross, fretful" first recorded 1520s. Related: Peevishly; peevishness.
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 Middle Dutch pegge "peg," a common Low German word (Low German pigge "peg," German Pegel "gauge rod, watermark," Middle Dutch pegel "little knob used as a mark," Dutch peil "gauge, watermark, standard"), of uncertain origin; perhaps from PIE *bak- "staff used as support" (see bacillus). 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 literal sense is uncertain (most of the likely candidates are not attested until centuries later). Peg leg "wooden leg" attested from 1765.
peg (v.): "fasten with or as if on a peg," 1590s, from peg (n.). Slang sense of "identify, classify" first recorded 1920. Related: Pegged; pegging.
Pegasus: winged horse in Greek mythology, late 14c., from Latin, from Greek Pegasos, usually said to be from pege "fountain, spring; a well fed by a spring" (plural 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 ending of the word indicates non-Greek origin. Advances since the 1990s in the study of the Luwians, neighbors of the Hittites in ancient Anatolia, show a notable convergence of the Greek name with Pihaššašši, the name of a Luwian weather-god: "the mythological figure of Pegasus carrying the lightning and thunderbolt of Zeus, ... is likely to represent an avatar of the Luwian Storm-God of Lightning ...." [Alice Mouton, et al., eds., "Luwian Identities," 2013]
Peggy: fem. familiar proper name, alteration of Maggie (see Margaret).
pegomancy (n.): "divination by fountains," 1727, from Latinized form of Greek pege "fountain, spring" (of unknown origin) + -mancy.
peignoir (n.): "lady's loose robe," 1835, from French peignoir, from Middle French peignouoir "garment worn over the shoulders while combing the hair" (16c.), from peigner "to comb the hair," from Latin pectinare, from pecten (genitive pectinis) "a comb," related to pectere "to comb" (see fight (v.)). 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 Old French Piers, nominative of proper name Pierre (see Peter) .
pejoration (n.): 1650s, noun of action from pejorate (see pejorative).
pejorative (adj.): "depreciative, disparaging," 1888, from French péjoratif, from Late Latin peiorat-, past participle stem of peiorare "make worse," from Latin peior "worse," related to pessimus "worst," pessum "downward, to the ground," from PIE *ped-yos-, comparative of root *ped- "to walk, stumble, impair" (see peccadillo). As a noun from 1882. English had a verb pejorate "to worsen" from 1640s.
Peking: former transliteration of what is now (in the pinyin system) called Beijing. In the Wade-Giles system it was Peiping; this form Peking pre-dates Wade-Giles and was formed by the old British-run, Hong Kong-based Chinese postal system.
Pekingese: 1907, "small long-haired dog of the pug type," so called because originally brought from the Imperial Palace at Peking, China. Also Pekinese.
pelage (n.): "coat of a mammal," from French pelage "hair or wool of an animal" (16c.), from Old French pel "hair," from Latin pilus "hair" (see pile (n.3)).
Pelagian: 1530s (n.); 1570s (adj.), from Medieval Latin 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 said to have been Morgan, literally "sea-dweller" (hence his Church name, from Greek pelagos "sea;" see pelagic). Related: Pelagianism.
pelagic (adj.): "pertaining to the sea," 1650s, from Latin pelagicus, from Greek pelagikos, from pelagos "sea, high sea, open sea, main," from PIE *pelag- "to spread out" (source of Greek plagos "side," Latin plaga "hunting net, curtain, region"), possibly from root *plak- (1) "to spread out, be flat" (see placenta).
Pelasgian: late 15c., "of the Pelasgi," from Latin Pelasgius, from Greek 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, literally "Sea-people" (see pelagic).
pelf (n.): mid-14c., "stolen goods," from Anglo-French pelf, Old French pelfre "booty, spoils" (11c.), of unknown origin; also see pilfer. Meaning "money, riches," with a pejorative overtone first recorded c. 1500.