31st

The term 31st is the ordinal form of the number 31, used to indicate position in a sequence. It appears in date notation, lists, rankings, and various naming conventions.

In English, ordinals are typically formed by adding a suffix to the cardinal number. For 31, the standard written form is thirty-first, and the numeral form is 31st. The suffix -st is generally used with numbers ending in 1, such as 21st and 31st, while the teens 11th, 12th, and 13th use -th. In other contexts hyphenation may occur, especially in written form of the full ordinal (thirty-first).

Date usage: The 31st day occurs in months with 31 days, namely January, March, May, July, August, October, and December. The 31st of December is widely celebrated as New Year’s Eve. In scheduling and archival work, a date labeled as the 31st can signify the last day of a month that has 31 days. The ordinal can also indicate annual anniversaries, such as the 31st edition of an event.

Other uses include toponymy and organizational names, where 31st is used in street names (for example, 31st Street) or in unit designations like the 31st Infantry Division. It also appears in lists, rankings, and ordinal descriptions across various domains.

Related terms include the written form thirty-first and other ordinal numbers in the English language.