*payoff* (Slang) =
1: A final payment or reward.E.g.: What's the payoff for finishing school? There are no good jobs even if you have your degree.
2: A bribe or illegal contribution of money to another; to bribe someone. E.g.: I wonder how much of a payoff the policeman got for not writing him a speeding ticket. You can't trust anyone these days--everyone has been paid off in one way or another.

Kickback = a return of a part of a sum received often because of confidential agreement or coercion. E.g.: Every city contract had been let with a ten percent kickback to city officials.

Hush money is an informal term for financial incentives or reward (bribery) offered in exchange for not divulging information.

Baksheesh is a Persian word, written بخشش and originating from the Pahlavi (Middle Iranian) language. It is a term used to describe tipping, charitable giving, and certain forms of political corruption and bribery in the Middle East and South Asia.