hush money       
noun [ U ]  informal uk/ˈhʌʃ ˌmʌn.i/ us/ˈhʌʃ ˌmʌn.i/
 封口钱
money that is given to someone to make them keep something secret
  She claimed that the politician had offered her hush money to keep their child a secret. 她声称那名政治人物给了她封嘴钱,不让她把他们有孩子的事说出去。