monthsis

Monthsis is a conceptual calendar system and timekeeping framework that aims to harmonize lunar and solar cycles by organizing the year into a fixed set of months. The term appears chiefly in speculative discussions of calendar reform and in science fiction settings, rather than as a widely adopted civil calendar.

Etymology and scope: The name monthsis blends the word month with a suffix suggesting a systematic process. In its proposed form, monthsis takes months as the primary units of time while seeking to reflect natural celestial rhythms through its structure and occasional intercalary days.

Structure and rules: A standard monthsis year comprises 13 months of 28 days each, totaling 364 days. To keep the calendar aligned with the solar year, one non-month day, called sol, is added at the end of the year. In leap years, a second extra day, sometimes referred to as sol2, is inserted, bringing the year to 366 days. The sol and sol2 days are not counted within any month and serve to realign the calendar with the solar cycle. Because each month has exactly 28 days, every month begins on the same weekday in a non-leap year, with small adjustments during leap years.

Usage and reception: Monthsis remains largely theoretical and is discussed mainly in the context of calendar reform debates and fiction. Proponents argue that its regular month length simplifies date arithmetic, scheduling, and weekly planning, while critics point to its deviation from established solar seasons, cultural timing, and the complexity of transitioning from existing calendars.

See also: Calendar reform, lunar calendar, solar calendar, ISO week date.