Twentyfifth

Twentyfifth is the ordinal form used to identify the position of twenty-five in a sequence. In standard English, ordinals from twenty to twenty-nine are written with a hyphen: twenty-fifth, twenty-sixth, twenty-seventh, and so on, and numerically as 25th. The non-hyphenated form “twentyfifth” is uncommon and typically found only in contexts that require no spaces or punctuation, such as certain filenames, identifiers, or stylistic choices.

The term is formed by combining the cardinal twenty with the ordinal fifth, using the ordinary English suffix -th to form ordinals. The word appears in historical, legal, and calendrical contexts as a descriptor of position rather than quantity. For example, the Twenty-Fifth Amendment to the United States Constitution concerns presidential succession and disability; the Twenty-Fifth Dynasty of Egypt refers to the Kushite dynasty around 747–656 BCE. The twenty-fifth day of a month is used in calendrical dating, for instance December 25 is Christmas Day in many countries. In mathematics, the number twenty-five is a perfect square (5 squared), and its ordinal form is used similarly when listing items or events.

See also: ordinal numbers, twenty-fourth, twenty-sixth, and related calendrical and historical uses.