Online Etymology Dictionary

peccadillo (n.): "slight sin," 1590s (earlier in corrupt form peccadilian, 1520s), from Spanish pecadillo, diminutive of pecado "a sin," from Latin peccatum "a sin, fault, error," noun use of neuter past participle of peccare "to miss, mistake, make a mistake, do amiss; transgress, offend, be licentious, sin," a word of uncertain origin. Watkins traces it to PIE *ped- (1) "a foot," via a verbal form meaning "to walk," with evolution to "to stumble, fall" then "to sin," perhaps via *ped-ko- "having a fault at the foot;" but de Vaan is suspicious: "there is no reference to feet in the meaning of peccare. And to 'make a faux pas' ... would hardly be rendered by the word for 'foot', but rather by 'walking.' " He finds a derivation from the root *pet- "to fall" (see petition (n.)) via *pet-ko- "a fall, error" to be "better semantically, but the addition of *-ko- to the bare root seems strange."
peccant (adj.): c. 1600, from Latin peccantem (nominative pecans) "sinful," present participle of peccare "to sin" (see peccadillo). As a noun from 1620s. Related: Peccancy.
peccary (n.): pig-like animal of South America, 1610s, from Carib (Guiana or Venezuela) pakira, paquira.
peccavi (v.): 1550s, Latin, literally "I have sinned;" past tense of peccare "to sin" (see peccadillo). Related: peccavimus "we have sinned;" peccavit "he has sinned."
peck (v.): c. 1300, possibly a variant of picken (see pick (v.)), or in part from Middle Low German pekken "to peck with the beak." Related: Pecked; pecking.
peck (n.1): late 13c., "dry measure of one-quarter bushel," of unknown origin; perhaps connected with Old French pek, picot (13c.), also of unknown origin (Barnhart says these were borrowed from English). Chiefly of oats for horses; original sense may be "allowance" rather than a fixed measure, thus perhaps from peck (v.).
peck (n.2): "act of pecking," 1610s, from peck (v.). It is attested earlier in thieves' slang (1560s) with a sense of "food, grub."
Peck's bad boy: "unruly or mischievous child," 1883, from fictional character created by George Wilbur Peck (1840-1916).
pecker (n.): "one who pecks," 1690s, agent noun from peck (v.); slang sense of "penis" is from 1902.
peckerwood (n.): 1859, U.S. Southern black dialectal inversion of woodpecker; in folklore, taken as the type of white folks (1929) and symbolically contrasted with blackbird.
pecking (n.): verbal noun from peck (v.), late 14c. As a behavior among hens, pecking order (1928) translates German hackliste (T.J. Schjelderuo-Ebbe, 1922); transferred sense of "human hierarchy based on rank or status" is from 1955.
peckish (adj.): "somewhat hungry," literally "disposed to peck," 1785, from peck (v.) + -ish. Related: Peckishly; peckishness.
Pecksniffian (adj.): 1851, after Mr. Pecksniff, unctuous hypocrite in Dickens' "Martin Chuzzlewit" (1844).
pectin (n.): polysaccharide found in fruit and vegetables, crucial in forming jellies and jams, 1838, from French pectine, coined early 1830s by French chemist Henri Braconnot (1781-1855) from acide pectique "pectic acid," a constituent of fruit jellies, from Greek pektikos "curdling, congealing," from pektos "curdled, congealed," from pegnynai "to make stiff or solid," from PIE root *pag-/*pak- "to join together" (see pact). Related: Pectic.
pectoral (adj.): 1570s, "pertaining to the breast," from Latin pectoralis "of the breast," from pectus (genitive pectoris) "breast, chest," from PIE root *peg- "breast."
pectoral (n.): early 15c., "ornament worn on the breast," from Middle French pectoral and directly from Latin pectorale "breastplate," noun use of neuter of adjective pectoralis (see pectoral (adj.)).

As a shortened form of pectoral muscle, attested from 1758. Slang shortening pec for this is first recorded 1966. Related: Pectorals; pecs.
peculate (v.): 1749, from Latin peculatus, past participle of peculari "to embezzle," from peculum "private property," originally "cattle" (see peculiar). Related: Peculated; peculating; peculator.
peculation (n.): 1650s, noun of action from Latin peculari (see peculate).
peculiar (adj.): mid-15c., "belonging exclusively to one person," from Latin peculiaris "of one's own (property)," from peculium "private property," literally "property in cattle" (in ancient times the most important form of property), from pecu "cattle, flock," related to pecus "cattle" (see pecuniary). Meaning "unusual" is first attested c. 1600 (earlier "distinguished, special," 1580s; for sense development, compare idiom). Related: Peculiarly.
peculiarity (n.): c. 1600, "exclusive possession;" 1640s, "special characteristic," from peculiar + -ity, or else from Latin peculiaritas. Meaning "an oddity" is attested by 1777. Related: Peculiarities.
pecuniary (adj.): c. 1500, from Latin pecuniarius "pertaining to money," from pecunia "money, property, wealth," from pecu "cattle, flock," from PIE root *peku- "wealth, movable property, livestock" (source of Sanskrit pasu- "cattle," Gothic faihu "money, fortune," Old English feoh "cattle, money").

Livestock was the measure of wealth in the ancient world, and Rome, like any other culture, was essentially a farmer's community. That pecunia was literally "wealth in cattle" was still apparent to Cicero. For a possible parallel sense development in Old English, see fee, and compare, evolving in the other direction, cattle. Compare also Welsh tlws "jewel," cognate with Irish tlus "cattle," connected via notion of "valuable thing," and, perhaps emolument.
pecunious (adj.): late 14c., from Latin pecuniosus "abounding in money," from pecunia "money" (see pecuniary). Related: Pecuniously; pecuniousness.
pedagogic (adj.): 1781, from Latin paedagogicus, from Greek paidagogikos "suitable for a teacher," from paidagogos "teacher" (see pedagogue).
pedagogical (adj.): 1610s, from Latin paedagogicus (see pedagogic) + -al (1). Related: Pedagogically.
pedagogue (n.): late 14c., "schoolmaster, teacher," from Old French pedagoge "teacher of children" (14c.), from Latin paedagogus, from Greek paidagogos "slave who escorts boys to school and generally supervises them," later "a teacher," from pais (genitive paidos) "child" (see pedo-) + agogos "leader," from agein "to lead" (see act (n.)). Hostile implications in the word are at least from the time of Pepys (1650s). Related: Pedagogal.
pedagogy (n.): 1580s, from Middle French pédagogie (16c.), from Latin paedagogia, from Greek paidagogia "education, attendance on boys," from paidagogos "teacher" (see pedagogue).
pedal (n.): 1610s, "lever (on an organ) worked by foot," from French pédale "feet, trick with the feet," from Italian pedale "treadle, pedal," from Late Latin pedale "(thing) of the foot," neuter of Latin pedalis "of the foot," from pes (genitive pedis) "foot," from PIE root *ped- (1) "a foot" (see foot (n.)).

Extended to various mechanical contrivances by 1789. Pedal steel guitar is from 1969. Pedal-pushers "type of women's trousers suitable for bicycling" is from 1944.
When college girls took to riding bicycles in slacks, they first rolled up one trouser leg, then rolled up both. This whimsy has now produced a trim variety of long shorts, called "pedal pushers." ["Life," Aug. 28, 1944]
pedal (v.): 1866 of musical organs, 1888 of bicycles, from pedal (n.). Related: Pedaled; pedaling.
pedant (n.): 1580s, "schoolmaster," from Middle French pédant (1560s) or directly from Italian pedante, literally "teacher, schoolmaster," of uncertain origin, apparently an alteration of Late Latin paedagogantem (nominative paedagogans), present participle of paedagogare (see pedagogue). Meaning "person who trumpets minor points of learning" first recorded 1590s.
pedantic (adj.): formed in English c. 1600, from pedant + -ic. The French equivalent is pédantesque. Perhaps first attested in John Donne's "Sunne Rising," where he bids the morning sun let his love and him linger in bed, telling it, "Sawcy pedantique wretch, goe chide Late schooleboyes." Related: Pedantical (1580s); pedantically.
pedanticism (n.): 19c., from pedantic + -ism. Earlier was pedantism (1590s).
pedantocracy (n.): 1842, from pedant + -cracy. Coined (in French) by Mill in a letter to Comte.
pedantry (n.): 1610s, from Italian pedanteria, from pedante, or from French pédanterie, from pédant (see pedant).
peddle (v.): "to retail," 1837 in modern use, a colloquial back-formation from peddler. Related: Peddled; peddling.
peddler (n.): late 14c. (c. 1300 as a surname, Will. Le Pedelare), from peoddere, peddere (c. 1200, mid-12c. as a surname), of unknown origin. It has the appearance of an agent noun, but no corresponding verb is attested in Middle English. Perhaps a diminutive of ped "panier, basket," also of unknown origin, but this is attested only from late 14c. Pedlar, preferred spelling in U.K., is attested from late 14c.
pederast (n.): 1730s, from French pédéraste, from Latin paederasta, from Greek paiderastes "a lover of boys" (see pederasty).
pederasty (n.): "sodomy of a man with a boy," c. 1600, from French pédérastie or directly from Modern Latin pæderastia, from Greek paiderastia "love of boys," from paiderastes "pederast, lover of boys," from pais (genitive paidos) "child, boy" (see pedo-) + erastes "lover," from erasthai "to love" (see Eros).
pedestal (n.): 1560s, "base supporting a column, statue, etc.," from Middle French piédestal (1540s), from Italian piedistallo "base of a pillar," from pie "foot" + di "of" + stallo "stall, place, seat," from a Germanic source (see stall (n.1)). Spelling in English influenced by Latin pedem "foot." An Old English word for it was fotstan, literally "foot-stone." Figurative sense of put (someone) on a pedestal "regard as highly admirable" is attested from 1859.
pedestrian (adj.): 1716, "prosaic, dull" (of writing), from Latin pedester (genitive pedestris) "plain, not versified, prosaic," literally "on foot" (sense contrasted with equester "on horseback"), from pedes "one who goes on foot," from pes (genitive pedis) "foot," from PIE root *ped- (1) "a foot" (see foot (n.)). Meaning "going on foot" is first attested 1791 in English (it also was a sense of Latin pedester). The earlier adjective in English was pedestrial (1610s).
pedestrian (n.): "walker," 1793, from pedestrian (adj.).
pediatric (adj.): 1849, from Greek paid-, stem of pais "child" (see pedo-) + -iatric.
pediatrician (n.): 1884, from pediatric + -ian.
pediatrics (n.): 1884; from pediatric; see -ics.
pedicel (n.): 1670s, from Modern Latin pedicellus, diminutive of pediculus (see pedicle).
pedicle (n.): "footstalk of a plant," 1620s, from Latin pediculus "footstalk, little foot," diminutive of pedem (nominative pes) "foot," from PIE root *ped- (1) "a foot" (see foot (n.)).
pediculosis (n.): "lice infestation," 1809, with -osis + pediculus, diminutive of pedis "a louse," said in some sources to be akin to pedere "to break wind" (see petard) on notion of "foul-smelling insect" [Watkins].
pediculous (adj.): "infested with lice; pertaining to lice," 1540s, from Latin pediculosus, from pediculus "louse" (see pediculosis).
pedicure (n.): 1839, "one whose business is surgical care of feet" (removal of corns, bunions, etc.), from French pédicure, from Latin pes (genitive pedis) "foot," from PIE root *ped- (1) "a foot" (see foot (n.)) + curare "to care for," from cura "care" (see cure (n.1.)). In reference to the treatment itself, attested from 1890; specifically as a beauty treatment, from 1900.
pedigree (n.): early 15c., "genealogical table or chart," from Anglo-French pe de gru, a variant of Old French pied de gru "foot of a crane," from Latin pedem accusative of pes "foot," from PIE root *ped- (1) "a foot" (see foot (n.)) + gruem (nominative grus) "crane," cognate with Greek geranos, Old English cran; see crane (n.)).

On old manuscripts, "descent" was indicated by a forked sign resembling the branching lines of a genealogical chart; the sign also happened to look like a bird's footprint. Form influenced in Middle English by association with degree. Meaning "ancestral line" is mid-15c.; of animals, c. 1600. Related: Pedigreed.
pediment (n.): triangular part of the facade of a Greek-style building, 1660s, alteration of periment, peremint (1590s), of unknown origin, "said to be a workmen's term" [OED]; probably a dialectal garbling of pyramid, the connection perhaps being the triangular shape. Sometimes associated with ped- "foot." Other possibilities include Latin pedamentum "vine-stalk, prop," and Italian pedamento, which at the time this word entered English meant "foundation, basework, footing." Meaning "base, foundation" is from 1726, by inflience of Latin pedem "foot."