mensis

Mensis is a Latin noun meaning month, a unit of time used in the Roman calendar. It denotes a calendar month and is encountered in classical and ecclesiastical Latin to refer to any month. In Latin text, months are often indicated as mensis followed by the month’s name in the genitive, for example mensis Ianuarii or mensis Martii, meaning the month of January or the month of March.

Etymology and usage: The term mensis derives from the Proto-Italic vocabulary for a monthly period tied to the lunar cycle. In practice, mensis appears in writings that date events or describe calendars, and it remains a standard way to speak of months in Latin, including medieval and scholarly Latin.

Calendar context: In the ancient Roman calendar, the concept of a month was closely linked to the lunar cycle, though reforms over time produced solar-year adjustments. The word mensis persisted through Latin literature and into ecclesiastical usage, where it continues to appear in phrases naming months or describing monthly time segments.

Related terms in English: The plural form menses in Latin denotes multiple months. In modern English, menses also refers to the menstrual period, a usage that reflects the same underlying idea of a recurring monthly cycle.

See also: Roman calendar, Julian calendar, Gregorian calendar, Latin language, ecclesiastical Latin.