thirteenth

Thirteenth is the ordinal form of the cardinal number thirteen, used to indicate position in a sequence. In English, it is formed by adding the ordinal suffix -th to the word thirteen, yielding thirteenth. It is used in various contexts to denote order, such as dates (the thirteenth of a month), enumerate items (the thirteenth item), or sports standings (the thirteenth place).

In mathematics, the thirteenth term refers to the element occupying the thirteenth position in a sequence. The concept of a thirteenth element or position is a general feature of counting and ordering systems, regardless of the specific subject.

The term also appears in formal names and titles, most notably the Thirteenth Amendment to the United States Constitution. Cultural associations with the number thirteen—often viewed as unlucky in Western cultures—can influence language and design choices, such as the avoidance of the number in building floor numbering or room designations in some places.

Linguistically, the form thirteenth reflects English conventions for forming ordinals from cardinal numerals, though the exact historical development varies across languages. In many contexts, the word functions similarly to other ordinals, marking a position within a defined order.

See also: Thirteen; Thirteenth Amendment; Triskaidekaphobia.