1 a playing card which has a single shape on it. An ace has either the lowest or the highest value in a game of cards 么点，爱司（纸牌游戏中分数最低或最高的纸牌）: the ace of spades 黑桃爱司 ☞Look at the note at card. 参看 card 的注释。

2 (in tennis) a SERVICE (= the first hit of the ball) that the person playing against you cannot hit back （网球）发球直接得分: to serve an ace 发球得分