Alternative spelling of twenty-one

The cardinal number occurring after twenty and before twenty-two, represented in Roman numerals as XXI and in Arabic numerals as 21.

(card games) Blackjack. / (sports) A basketball-based game in which players attempt to score exactly twenty-one points.

The start of the twenty-second hour of the day on the 24-hour clock i.e. 21:00. / The number two thousand one hundred. / The year 2100.

(US, archaic, used by and usually of white people) Beholden to no one; master of one's own destiny.