twenty-one /ˌtwɛntiˈwʌn/noun 2number 1 noun2 •Blackjack.They were to spend many an evening together sitting round the old kitchen table playing twentyone …. — 1978 •A basketball-based game in which players attempt to score exactly twenty-one points. number1 •The cardinal number occurring after twenty and before twenty-two, represented in Roman numerals as XXI and in Arabic numerals as 21.
