word-forming element meaning "cold," from Latinized form of Greek psykhros "cold," from psykhrein "blow, make cool or cold," perhaps from the same root as psyche.

before vowels pter-, word-forming element in science meaning "feather; wing," from Greek pteron "wing," from PIE *pt-ero- (source also of Sanskrit patram "wing, feather," Old Church Slavonic pero "pen," Old Norse fjöðr, Old English feðer), from root *pet- "to rush; to fly."

as an element in names of chemicals derived from benzene, from French phène, proposed 1836 by French scientist Auguste Laurent as an alternative name for "benzene" because it had been found in coal tar, a byproduct of the manufacture of "illuminating gas," from Greek phainein "bring to light, cause to appear, show" (from PIE root *bha- (1) "to shine").

in compounds, "having a weight of (a specified number of) pounds," 1680s, from pound (n.1).