a playing card with a large single symbol on it, which has either the highest or the lowest value in a particular card game A 纸牌（亦称 “爱司”） 
the ace of spades/hearts/diamonds/clubs 黑桃／红心／方块／梅花 A
Oxford Collocations Dictionaryadjective- fighter
- flying
- goal
- …
- (informal)
a person who is very good at doing something 擅长…的人；精于…的人 a soccer/flying ace 足球／飞行顶尖高手 an ace marksman 神枪手 French ace Mbappé scored a late penalty. 法国王牌姆巴佩罚进了一个点球。
Oxford Collocations Dictionaryadjective- fighter
- flying
- goal
- …
(in tennis 网球 a serve (= the first hit) that is so good that your opponent cannot reach the ball 发球得分；爱司球 Oxford Collocations Dictionaryadjective- fighter
- flying
- goal
- …
(in golf 高尔夫球 an occasion when a player hits the ball from the tee into the hole using only one shot 一种情况下，玩家仅使用一个射击代名词“一杆入洞”就将球从发球台打入洞中
Word OriginMiddle English (denoting the “one” on dice): via Old French from Latin as ‘unity, a unit’.
Idioms
an ace up your sleeve (British English)
(North American English an ace in the hole)
- (informal)
a secret advantage, for example a piece of information or a skill, that you are ready to use if you need to 秘藏的王牌；撒手锏；锦囊妙计
hold all the aces
to have all the advantages in a situation 占尽天时地利人和 The union soon realized that the management held all the aces. 工会很快意识到管理层掌握着所有的王牌。
play your ace
to use your best argument, etc. in order to get an advantage in a situation 打出王牌；使出绝招
within an ace of something/of doing something