/ eɪs; NAmE / noun , adjective
■ noun
1.
a playing card with a large single symbol on it, which has either the highest or the lowest value in a particular card game :
the ace of spades / hearts / diamonds / clubs
2.
( informal ) a person who is very good at doing sth :
a soccer / flying ace
an ace marksman
3.
( in tennis ) a serve (= the first hit) that is so good that your opponent cannot reach the ball :
He served 20 aces in the match.
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IDIOMS
- an ace up your sleeve
- hold all the aces
- play your ace
- within an ace of sth / of doing sth
■ adjective
( informal ) very good :
We had an ace time.
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WORD ORIGIN
Middle English (denoting the “one” on dice): via Old French from Latin as unity, a unit.