Source : WordNet®

twenty-one
     adj : being one more than twenty [syn: {21}, {xxi}]
     n 1: the cardinal number that is the sum of twenty and one [syn:
          {21}, {XXI}]
     2: a gambling game using cards; the object is to hold cards
        having a higher count than those dealt to the bank up to
        but not exceeding 21 [syn: {blackjack}, {vingt-et-un}]