before vowels pneum-, word-forming element meaning "lung," from Greek pneumōn "lung," altered (probably by influence of pnein "to breathe") from pleumōn (which was an alternative form in Attic), literally "floater," probably cognate with Latin pulmo "lung(s)," from PIE root *pleu- "to flow." The notion perhaps is from the fact that, when thrown into a pot of water, lungs of a slaughtered animal float, while the heart, liver, etc., do not (compare Middle English lights "the lungs," literally "the light (in weight) organs").  

word-forming element from Greek pōgōn "the beard," which is of unexplained origin. Used in Pogonophile (by 1961); pogonophobia (1852).

word-forming element meaning "political; political and," from Latinized combining form of Greek politikos (see political).

word-forming element meaning "many, much, multi-, one or more," from Greek polys "much" (plural polloi), from PIE root *pele- (1) "to fill," with derivatives referring to multitudinousness or abundance. Equivalent to Latin multi-, it is properly used in compounds only with words of Greek origin. In chemical names, usually indicating a compound with a large number of atoms or molecules of the same kind (such as polymer).

word-forming element meaning "river," from Greek potamos "river," perhaps literally "rushing water," from PIE root *pet- "to rush, to fly."

from Latin adverb and preposition praeter "beyond, past, besides, except" (from PIE root *per- (1) "forward," hence "in front of, before"). See preter-, which now is the usual form of it in English; also see æ (1).