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month

Irregular unit of time dividing a calendar year

Entityunit of time unit without standard conversion to SI UCUM derived unitQ5151

Also known as months

Instance of: unit of time
, unit without standard conversion to SI
, UCUM derived unit
Subclass of: time interval with respect to recurring time interval
, calendar system
, orbit of the Moon
Part of: year
, calendar

Overview

From Wikipedia, the free encyclopedia · Read full article · Text CC BY-SA 4.0

A month is a unit of time, used with calendars, that is approximately as long as a natural phase cycle of the Moon; the words month and Moon are cognates. The traditional concept of months arose with the cycle of Moon phases; such lunar months ("lunations") are synodic months and last approximately 29.53 days, making for roughly 12.37 such months in one Earth year. From excavated tally sticks, researchers have deduced that people counted days in relation to the Moon's phases as early as the Paleolithic age. Synodic months, based on the Moon's orbital period with respect to the Earth–Sun line, are still the basis of many calendars today and are used to divide the year.

Overview

All data

100 statements · 12% with external sources · numbers in brackets are citations

On other databases

54 identifiers linking month across the web's reference databases

Data quality

100

statements

12%

externally sourced

Source last edited October 5, 2026. AIDB refreshes this page daily.

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AIDB. (2026). month (Q5151). Retrieved from https://aidb.si/e/month-Q5151