I. | ̷ ̷ ̷ ̷| ̷ ̷ adjective
1. : being number 51 in a countable series
the fifty-first day
— see number table
2. : being one of 51 equal parts into which something is divisible
a fifty-first share of the money
II. noun
1. : number 51 in a countable series
2. : the quotient of a unit divided by 51 : one of 51 equal parts of something
one fifty-first of the total