noun

• (card games) A playing card showing a single pip, typically the highest or lowest ranking card in a game.
  "You see, Sir, when I look at the Ace it reminds me that there is but one God. The deuce reminds me that the bible is divided into two parts; the Old and New Testaments. And when I see the trey I think of the Father, Son and Holy Ghost."
• (dice games) A die face marked with a single dot, typically representing the number one.
• (US, slang) A dollar bill.
  "[…] maybe two or three twenties, a dozen tens, and twenty or thirty fins. The rest is all aces and silver."
• (tennis, volleyball) A serve won without the opponent hitting the ball.

verb

• (transitive, US, informal) To pass (a test, interviews etc.) perfectly.
• (ambitransitive, US, informal) To defeat (others) in a contest; to outdo (others) in a competition.
• (ambitransitive, tennis) To win a point against (an opponent) by an ace.
• (golf) To make an ace (hole in one).

adj

• (UK, slang) Excellent.

adj

• (slang) Asexual, not experiencing sexual attraction.
  ""Some people who identify as ace fall under the GLBT umbrella while many others do not. Members of the queer movement have reached out to asexuals to include them in their community. The acronym for this has now become GLBTQA (gay, lesbian, bisexual, transgender, questioning, and asexual).""