kickback (n.)youdaoicibaDictYouDict[kickback 词源字典]
also kick-back, c. 1900 in various mechanical senses, from kick (v.) + back (adv.). By 1926 in a slang sense of "be forced to return pelf, pay back to victims," which was extended to illegal partial give-backs of government-set wages that were extorted from workers by employers. Hence sense of "illegal or improper payment" (1932).[kickback etymology, kickback origin, 英语词源]