xxi
1. [ adjective ] being one more than twenty
Synonyms: 21 twenty-one
Related terms: cardinal
2. [ noun ] (mathematics) the cardinal number that is the sum of twenty and one
Synonyms: 21 twenty-one
Related terms: large_integer
Similar spelling:   xxxi
  XXII
  XX
  xxxii
  XXIII
  xxy
  xxxiii
  XXX
  XIX