slush fund
noun [ C ] uk/ˈslʌʃ ˌfʌnd/ us/ˈslʌʃ ˌfʌnd/
（用于政治或商业目的的）非法基金，行贿基金
an amount of money that is kept for dishonest or illegal activities in politics or business
He used his party's slush fund to buy votes in the election. 他用所属政党的非法基金贿赂选民投他的票。