before vowels coen-, word-forming element meaning "common," from Latinized form of Greek koinos "common, public, shared, general, ordinary," from PIE *kom "beside, near, by, with" (see com-).
An initial consonant combination common in Greek; the p- typically is silent in English words that have it but pronounced in French, German, etc.
word-forming element common in words of French and Latin origin, meaning primarily "through," thus also "throughout; thoroughly; entirely, utterly," from Latin preposition per (see per (prep.)).
also pleo-, word-forming element meaning "more," from Greek pleiōn "larger, greater in quantity, the more part, very many" (comparative of polys "much"), from PIE *ple- (source also of Latin plere "to fill," plebes, "the populace, the common people;" Greek plēthein "be full," plērēs "full"), possibly a variant of root *pele- (1) "to fill."
initial consonant combination used in Old English (the Clark Hall dictionary has 82 entries under cn-), but not now admitted in speech, the n- only being sounded. In Middle English spelling all were lost or turned to kn-. It also is retained in the spelling of some Latinized words from Greek, where initial kn- was common.