twelfth

Twelfth is the ordinal form of the number twelve. It designates position in a sequence of twelve items, coming after the eleventh and before the thirteenth. In English spelling and pronunciation, twelfth is pronounced with a hard f-th ending: /ˈtwɛlfθ/. The word derives from Old English twelfta, itself from twelf, meaning twelve; over time the suffix evolved into the standard ordinal form twelfth.

As a noun, a twelfth refers to one of twelve equal parts of a whole, i.e., a 1/12 share. In fractions, the symbol or term “twelfth” denotes the ratio 1/12. In calendar and time contexts, the twelfth can appear in dates (the twelfth of January), in describing centuries (the twelfth century), or in unit systems that divide things into dozens.

In common usage, the number twelve appears in many domains, such as the base-12 (duodecimal) system, where dozen and gross (12 and 144) are familiar groupings. The base-12 concept remains visible in everyday measures, like inches in a foot and months in a year.

In music theory, the twelfth is a compound interval equal to an octave plus a perfect fifth; while less common in everyday practice, it is recognized as a specific interval in theoretical contexts.

Culturally, the term appears in Shakespeare’s play Twelfth Night, which is set around the Epiphany festival. The phrase also refers to the eve of Epiphany (often celebrated as Twelfth Night in various traditions). The form twelfth is used across disciplines to denote the ordinal position, a fraction, a time or date reference, or a musical interval.