hush money

Cash given to assure the silence of the receiver, as in a bribe. An example is a payoff to an employee who uncovers theft in the organization.

A bribe paid to keep something secret, as in No amount of hush money will keep that scandal from coming out. [c. 1700]

The noun has one meaning:

Meaning #1: a bribe paid to someone to insure that something is kept secret