Duodecima

Duodecima is the feminine form of the Latin ordinal duodecimus, meaning "the twelfth." It is used in Latin to denote the twelfth item in a series and to modify feminine nouns in enumerations, titles, and phrases. In classical and medieval Latin, common expressions include duodecima hora (the twelfth hour) and duodecima pars (the twelfth part).

Beyond direct enumeration, the form appears in scholarly and religious texts when listing sections, chapters, or ordinals that are feminine in gender. In musical and theoretical contexts, the term appears in some European treatises as a designation for the interval known in English as the twelfth—the octave plus a fifth—though in modern usage this interval is usually referred to with the equivalent local form such as Italian dodicesima or Spanish duodécima.

Etymology: from Latin duodecimus (twelfth) with the feminine suffix -a, yielding duodecima for feminine nouns. In many Romance languages, the corresponding ordinal forms derive from the same root but bear their own spellings (for example, Spanish duodécima, Italian dodicesima, French douzième, though not direct cognates in all cases).

Because duodecima is primarily a Latin form, it is most commonly encountered in scholarly, liturgical, and historical texts rather than in everyday use. It remains a standard example of how Latin adjectives agree with gender and number in nominal phrases. See also duodecimal, the base-12 numeral system, and related Latin ordinal forms.