xxi xxi /ˈdʌbəl ɛks aɪ/

adjective

1. Being one more than twenty  ( xxi , twenty-one , 21 )
   being one more than twenty
   

 XXI

noun

1. The cardinal number that is the sum of twenty and one  ( XXI , twenty-one , 21 )
   the cardinal number that is the sum of twenty and one
    The legal drinking age in the US is twenty-one
   The legal drinking age in the US is twenty-one