I. | ̷ ̷ ̷ ̷| ̷ ̷ adjective
: being one more than 30 in number
thirty-one years
— see number table
II. pronoun, plural in construction
: 31 countable persons or things not specified but under consideration and being enumerated
thirty-one are here
thirty-one were found
III. noun
1. : one and 30
2.
a. : 31 units or objects
a total of thirty-one
b. : a group or set of 31
3. : the numerable quantity symbolized by the arabic numerals 31
4.
[translation of French trente et un ]
: any of various games played with cards, dice, or numbers in which the winner is the player whose score equals or most nearly approaches 31