1. Being one more than twenty
   - 21, xxi

1. The cardinal number that is the sum of twenty and one
   - 21, XXI
    
2. A gambling game using cards; the object is to hold cards having a higher count than those dealt to the banker up to but not exceeding 21
   "Vingt-et-un is the French name for the game commonly known as twenty-one";
   - blackjack, vingt-et-un, pontoon [Brit]

Derived forms: twenty-ones

See also: cardinal

Type of: card game, cards, large integer

Encyclopedia: Twenty-one