1 to accept or admit that sth is true or exists 承认；认定；确认: He acknowledged (the fact) that he had made a mistake. 他承认自己犯了错误。He is acknowledged to be the country's greatest writer. 大家公认他是全国最伟大的作家。

2 to show that you have seen or noticed sb/sth or received sth 答理；表示收悉: The manager sent a card to all the staff to acknowledge their hard work. 经理给全体人员发了感谢卡，对他们努力工作表示感谢。