before vowels petr-, word-forming element used from 19c., indicating "rock, stone" (in anatomy it refers to the petrous parts of certain bones), from Greek petros "stone, boulder," petra "rock, rocky mountain range, cliff" (see petrous).

word-forming element meaning "eating," from Greek phago- "eating, devouring," from PIE root *bhag- "to share out, apportion; to get a share." As in Phagiphany, the name of the Church festival celebrating the miracle of the fishes and loaves.

before vowels phaner-, word-forming element meaning "visible, manifest," especially from 18c. in biology, from Greek phaneros "visible, manifest, evident, apparent," from phainein "bring to light, cause to appear, show," from PIE root *bha- (1) "to shine." Opposed to crypto-.

word-forming element meaning "drug, medicine," also "poison," from Latinized form of Greek pharmakon "drug, poison" (see pharmacy).

before vowels phen-, word-forming element in science meaning "pertaining to or derived from benzene;" see -phene.

before vowels phil-, word-forming element meaning "loving, fond of, tending to," from Greek philos (adj.) "dear, loved, beloved," as a noun, "friend," from philein "to love, regard with affection," a word of unknown origin. Productive of a great many compounds in ancient Greek (such as philokybos "a lover of dice-play"). Opposed to miso-. Compare -phile.

word-forming element in medicine meaning "a vein or veins," from Greek phlebo-, combining form of phleps "vein," a word of uncertain origin.

word-forming element meaning "sound, voice," from Greek phōno-, combining form of phōnē "voice, sound," from PIE root *bha- (2) "to speak, tell, say."

word-forming element meaning "light" or "photographic" or "photoelectric," from Greek photo-, combining form of phos (genitive photos) "light," from PIE root *bha- (1) "to shine."