I. | ̷ ̷ ̷ ̷| ̷ ̷ adjective
1. : being number 21 in a countable series
the twenty-first day
— see number table
2. : being one of 21 equal parts into which something is divisible
a twenty-first share of the money
II. noun
1. : number 21 in a countable series
the twenty-first of the month
2. : the quotient of a unit divided by 21 : one of 21 equal parts of something
one twenty-first of the total