N-VAR 废除;取消;宣告无效 The annulment of a contract or marriage is an official declaration that it is invalid, so that legally it is considered never to have existed. 废除;取消;宣告无效
...the annulment of the elections. [+ of]
选举被宣告无效
He may appeal to the Pope for an annulment of his 24-year marriage.