- A playing card with a single pip or spot on it, ranked as the highest card in its suit in most card games.
- A serve that an opponent is unable to return in tennis or other racket games.
- A pilot with a high number of air victories in air combat.
Late 19th century: from french as, from latin as "unit," used in games to denote a playing card with a single spot or pip.
- He held four aces in his hand.
- The player hit an ace on the serve.
- The ace fighter pilot had down 20 enemy planes.
- The ace in the deck allowed him to win the game.
- The tennis player's serve was nearly always an ace.