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."