hush money n 1: a bribe paid to someone to insure that something is kept secret
Hush \Hush\, n. Stillness; silence; quiet. [R.] "It is the hush of night." --Byron. [1913 Webster] {Hush money}, money paid to secure silence, or to prevent the disclosure of facts. --Swift. [1913 Webster]
26 Moby Thesaurus words for "hush money": account, allowance, assessment, bill, blackmail, blood money, boodle, bribe, bribe money, emolument, fee, footing, gratification, gratuity, initiation fee, mileage, payoff, payola, protection, reckoning, retainer, retaining fee, scot, sop, stipend, tribute