polypeptide (n.)

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).

"short chain of amino acids linked by amide bonds," 1906, from German peptid (1902); see peptone + -ide, here probably indicating a derivative. Related: Peptidic.