Ace (noun)

1. A playing card with a single pip or spot on it, ranked as the highest card in its suit in most card games.
2. A serve that an opponent is unable to return in tennis or other racket games.
3. A pilot with a high number of air victories in air combat.

Origin:

Late 19th century: from french as, from latin as "unit," used in games to denote a playing card with a single spot or pip.

Examples:

1. He held four aces in his hand.
2. The player hit an ace on the serve.
3. The ace fighter pilot had down 20 enemy planes.
4. The ace in the deck allowed him to win the game.
5. The tennis player's serve was nearly always an ace.