Online Etymology Dictionary

petrodollar (n.): 1974, "surplus of petroleum exports over imports of all other goods," as a notational unit of currency (in reference to OPEC nations), formed in English from petro- (2) + dollar.
petroglyph (n.): 1870, from French pétroglyphe, from Greek petra "rock" (see petrous) + glyphe "carving" (see glyph).
petrol (n.): "gasoline," 1895, from French pétrol (1892); earlier used (1580s) in reference to the unrefined substance, from Middle French petrole "petroleum," from Old French (13c.), from Medieval Latin petroleum (see petroleum).
petroleum (n.): early 15c. "petroleum, rock oil" (mid-14c. in Anglo-French), from Medieval Latin petroleum, from Latin petra "rock" (see petrous) + oleum "oil" (see oil (n.)).
petrology (n.): 1811 (erroneously as petralogy), from petro- (1) "rock" + -ology.
Petronilla: also Petronella, fem. proper name, a feminine diminutive of Latin Petronius. Also "the name of a saint much-invoked against fevers and regarded as a daughter of St. Peter. The name was accordingly regarded to be a derivative of Peter and became one of the most popular of girls' names, the vernacular Parnell being still used as a proper name as late as the 18th century in Cornwall" [Reaney].
petrous (adj.): 1540s, from Middle French petreux, from Latin petrosus "stony," from petra "rock," from Greek petra "rock, cliff, ledge, shelf of rock, rocky ridge," of uncertain origin. Possibly from PIE root *per- (2) "to lead, pass over," if the original meaning is "bedrock" and the notion is "what one comes through to" [Watkins].
petticoat (n.): early 15c., pety coote, literally "a small coat," from petty + coat (n.). Originally a padded coat worn by men under armor, applied mid-15c. to a garment worn by women and young children. By 1590s, the typical feminine garment, hence a symbol of female sex or character.
Men declare that the petticoatless female has unsexed herself and has left her modesty behind. ["Godey's Magazine," April 1896]
pettifogger (n.): 1560s, from petty; the second element possibly from obsolete Dutch focker, from Flemish focken "to cheat," or from cognate Middle English fugger, from Fugger the renowned family of merchants and financiers of 15c.-16c. Augsburg. In German, Flemish and Dutch, the name became a word for "monopolist, rich man, usurer."
A 'petty Fugger' would mean one who on a small scale practices the dishonourable devices for gain popularly attributed to great financiers; it seems possible that the phrase 'petty fogger of the law,' applied in this sense to some notorious person, may have caught the popular fancy. [OED first edition, in a rare burst of pure speculation]
However, OED also calls attention to pettifactor "legal agent who undertakes small cases" (1580s), which, though attested slightly later, might be the source of this. Related: Pettifoggery.
pettifogging: 1570s as a verbal noun; c. 1600 as a past participle adjective; see pettifogger. A verb pettifog is rare and attested only from 1640s.
petting (n.): 1873, "fondling indulgence," verbal noun from pet (v.). Meaning "amorous caressing, foreplay" is from 1920 (in F. Scott Fitzgerald).
pettish (adj.): 1550s, "impetuous," evidently from pet (n.2) in its "ill humor" sense + -ish. Meaning "peevish, easily annoyed" is from 1590s.
It has naturally been assoc. with PET sb.1, as being a characteristic habit of a "pet" or indulged and spoiled child; but the connexion of sense is not very clear or simple .... [OED]
Related: Pettishly; pettishness.
petty (adj.): late 14c., "small," from phonemic spelling of Old French petit "small" (see petit). In English, not originally disparaging (as still in petty cash, 1834; petty officer, 1570s). Meaning "of small importance" is recorded from 1520s; that of "small-minded" is from 1580s. Related: Pettily; pettiness. An old name for "Northern Lights" was petty dancers.
petulance (n.): c. 1600, "insolence, immodesty," from French pétulance (early 16c.), from Latin petulantia "sauciness, impudence," noun of quality from petulantem (see petulant). Meaning "peevishness" is recorded from 1784, from influence of pettish, etc. It displaced earlier petulancy (1550s).
petulant (adj.): 1590s, "immodest, wanton, saucy," from Middle French petulant (mid-14c.), from Latin petulantem (nominative petulans) "wanton, froward, saucy, insolent," present participle of petere "to attack, assail; strive after; ask for, beg, beseech" (see petition (n.)). Meaning "peevish, irritable" first recorded 1775, probably by influence of pet (n.2). Related: Petulantly.
petunia (n.): 1825, from Modern Latin Petunia (1789), from French petun (16c.), an obsolete word for "tobacco plant," from Portuguese petum, evidently from Guarani (Paraguay) pety. The petunia has a botanical affinity to the tobacco plant. See tobacco.
pew (n.): late 14c., "raised, enclosed seat for certain worshippers" (ladies, important men, etc.), from Old French puie, puy "balcony, elevation," from Latin podia, plural of podium "elevated place," also "balcony in a Roman theater" (see podium). Meaning "fixed bench with a back, for a number of worshippers" is attested from 1630s.
pewee (n.): "flycatcher, lapwing," 1810, variant of pewit (q.v.). See also peewee.
pewit (n.): "lapwing" (still the usual name for it in Scotland), 1520s, imitative of its cry (compare Flemish piewit-voghel, Middle Low German kivit, German kiwitz; also see kibitz).
pewter (n.): early 14c., "any of various alloys having tin as their main constituent" (the usual form is one part lead to four parts tin), from Old French peautre (12c.), from Vulgar Latin *peltrum "pewter" (source of Spanish peltre, Italian peltro), of uncertain origin. Related: Pewterer.
peyote (n.): "mescal cactus," 1849, from Mexican Spanish peyote, from Nahuatl (Aztecan) peyotl, said to mean "caterpillar;" the cactus so called from the downy button on top.
Pez: Austrian candy product, in U.S. use by 1956, said to be from letters in German Pfefferminz "peppermint."
pH: 1909, from German PH, introduced by S.P.L. Sörensen, from P, for German Potenz "potency, power" + H, symbol for the hydrogen ion that determines acidity or alkalinity.
ph: now in English usually representing "f," originally it was the combination used by Romans to represent Greek letter phi (cognate with Sanskrit -bh-, Germanic -b-), which at first was an aspirated "p," later the same sound as German -pf-. But by 2c. B.C.E. had become a simple sound made by blowing through the lips (bilabial spirant).

Roman "f," like modern English "f," was dentilabial; by c. 400, however, the sounds had become identical and in some Romanic languages (Italian, Spanish), -ph- regularly was replaced by -f-. This tendency took hold in Old French and Middle English, but with the revival of classical learning the words subsequently were altered back to -ph- (except fancy and fantastic), and due to zealousness in this some non-Greek words in -f- began to appear confusedly in -ph-, though these forms generally have not survived.
Ph.D: attested from 1869; abbreviation of Latin Philosophiae Doctor "Doctor of Philosophy."
phaeton (n.): type of light four-wheeled carriage, 1742, from French (1735), from Greek Phaethon name of the son of Helios and Clymene, who tried to drive his father's sun-chariot but crashed after almost setting fire to the whole earth. His name is literally "shining," from phaein "to shine, gleam," from phaos "light" (see fantasy). Earlier as a name for a reckless driver (1590s).
phage (n.): virus that destroys bacteria, 1917, an abbreviated form of bacteriophage.
phago-: word-forming element meaning "eating," from Greek phago- "eating, devouring," (see -phagous).
phagocyte (n.): 1884, from German phagocyten (plural), coined in German in 1884 by Dr. Elias Metchnikoff (1845-1916) from Greek phago- "eating, devouring" (see -phagous) + -cyte (see cyto-). Related: Phagocytosis.
phalange (n.): mid-15c., "phalanx, ancient military division," from Middle French phalange "phalanx" (13c.), from Latin phalangem (nominative phalanx); see phalanx. It is the earlier form of this word in English.
phalanstery (n.): 1846, from French phalanstère, name for one of the socialistic communities of c.1,800 people, living together as family, proposed as the basic unit of society in the system of French social scientist François-Marie-Charles Fourier (1772-1837), coined by Fourier from phalange, properly "phalanx" (see phalanx) + ending after monastère "monastery."
phalanx (n.): 1550s, "line of battle in close ranks," from Latin phalanx "compact body of heavily armed men in battle array," or directly from Greek phalanx (genitive phalangos) "line of battle, battle array," also "finger or toe bone," originally "round piece of wood, trunk, log," of unknown origin. Perhaps from PIE root *bhelg- "plank, beam" (source of Old English balca "balk;" see balk (n.)). The Macedonian phalanx consisted of 50 close files of 16 men each. In anatomy, originally the whole row of finger joints, which fit together like infantry in close order. Figurative sense of "number of persons banded together in a common cause" is attested from 1600 (compare Spanish Falangist, member of a fascist organization founded in 1933).
phallic (adj.): "pertaining to the phallus," 1789, from Greek phallikos, from phallos (see phallus). First record of phallic symbol is from 1809.
phallocentric (adj.): 1927, from comb. form of phallus + -centric.
phallus (n.): 1610s, "an image of the penis," from Latin phallus, from Greek phallos "penis," also "carving or image of an erect penis (symbolizing the generative power in nature) used in the cult of Dionysus," from PIE *bhel-no-, from root *bhel- (2) "to blow, inflate, swell" (source also of Old Norse boli "bull," Old English bulluc "little bull," and possibly Greek phalle "whale;" see bole). Used of the penis itself (often in symbolic context) from 1924, originally in jargon of psychoanalysis.
phanero-: before vowels phaner-, word-forming element meaning "visible, manifest," from Greek phanero-, comb. form of phaneros "visible, manifest," from phainein "to show" (see phantasm).
phantasm (n.): early 13c., fantesme, from Old French fantosme "a dream, illusion, fantasy; apparition, ghost, phantom" (12c.), and directly from Latin phantasma "an apparition, specter," from Greek phantasma "image, phantom, apparition; mere image, unreality," from phantazein "to make visible, display," from stem of phainein "to bring to light, make appear; come to light, be seen, appear; explain, expound, inform against; appear to be so," from PIE root *bha- (1) "to shine" (source also of Sanskrit bhati "shines, glitters," Old Irish ban "white, light, ray of light"). Spelling conformed to Latin from 16c. (see ph). A spelling variant of phantom, "differentiated, but so that the differences are elusive" [Fowler].
phantasma (n.): 1590s, from Latin phantasma (see phantasm).
phantasmagoria (n.): 1802, name of a "magic lantern" exhibition brought to London in 1802 by Parisian showman Paul de Philipstal, the name an alteration of French phantasmagorie, said to have been coined 1801 by French dramatist Louis-Sébastien Mercier as though to mean "crowd of phantoms," from Greek phantasma "image, phantom, apparition" (see phantasm) + second element probably a French form of Greek agora "assembly" (but this may have been chosen more for the dramatic sound than any literal sense). Transferred meaning "shifting scene of many elements" is attested from 1822. Related: Phantasmagorical.
phantasmal (adj.): 1813, from phantasm + -al (1). Related: Phantasmally.
phantom (n.): c. 1300, fantum "illusion, unreality," from Old French fantosme (12c.), from Vulgar Latin *fantauma, from Latin phantasma "an apparition" (see phantasm). The ph- was restored in English late 16c. (see ph). Meaning "specter, spirit, ghost" is attested from late 14c.; that of "something having the form, but not the substance, of a real thing" is from 1707. As an adjective from early 15c.
pharaoh (n.): title of the kings of ancient Egypt, Old English Pharon, from Latin Pharaonem, from Greek Pharao, from Hebrew Par'oh, from Egyptian Pero', literally "great house."
pharisaic (adj.): 1610s, from Church Latin pharisaicus, from Greek pharisaikos, from pharisaios (see Pharisee). Related: Pharisaical (1530s).
Pharisee (n.): from Old English Fariseos, Old French pharise (13c.), and directly from Late Latin Pharisæus, from Greek Pharisaios, from Aramaic perishayya, emphatic plural of perish "separated, separatist," corresponding to Hebrew parush, from parash "he separated." Ancient Jewish sect (2c. B.C.E.-1c. C.E.) distinguished by strict observance but regarded as pretentious and self-righteous, at least by Jesus (Matt. xxiii:27). Meaning "self-righteous person, formalist, hypocrite" is attested from 1580s.
pharmaceutical (adj.): 1640s (pharmaceutic in the same sense is from 1540s), from Late Latin pharmaceuticus "of drugs," from Greek pharmakeutikos, from pharmakeus "preparer of drugs, poisoner" (see pharmacy). Related: Pharmaceuticals; pharmaceutically.
pharmacist (n.): 1811; see pharmacy + -ist. Replaced obsolete pharmacian (1720). The Latin word was pharmacopola, the Greek pharmakopoles.
pharmacokinetics (n.): 1960, from pharmaco- + kinetic.
pharmacologist (n.): 1728, from pharmacology + -ist.
pharmacology (n.): 1721, formed in Modern Latin (1680s) from pharmaco- + -logy. Related: Pharmacological.
pharmacopeia (n.): also pharmacopoeia, "official book listing drugs and containing directions for their preparation," 1620s, from medical Latin, from Greek pharmakopoiia "preparation of drugs," from pharmakon "drug" (see pharmacy) + poiein "to make" (see poet). First used as a book title by Anutius Foesius (1528-1595) of Basel. Related: Pharmacopeial.