|1.||one of the twelve divisions (calendar months) of the calendar year|
|2.||a period of time extending from one date to a corresponding date in the next calendar month|
|3.||a period of four weeks or of 30 days|
|4.||the period of time (tropical month) taken by the moon to return to the same longitude after one complete revolution around the earth; 27.321 58 days (approximately 27 days, 7 hours, 43 minutes, 4.5 seconds)|
|5.||the period of time (sidereal month) taken by the moon to make one complete revolution around the earth, measured between two successive conjunctions with a distant star; 27.321 66 days (approximately 27 days, 7 hours, 43 minutes, 11 seconds)|
|6.||Also called: lunation the period of time (lunar or synodic month) taken by the moon to make one complete revolution around the earth, measured between two successive new moons; 29.530 59 days (approximately 29 days, 12 hours, 44 minutes, 3 seconds)|
|7.||informal a month of Sundays a long unspecified period|
|[Old English mōnath; related to Old High German mānōd, Old Norse mānathr; compare Gothic mena moon]|
The average time between successive occurrences of the same phase of the Moon, equal to approximately 29 days, 12 hours, 44 minutes. Depending on the lunar calendar being used, a lunar month can begin with the new moon or the full moon. Also called lunation, synodic month. ◇ A period of 12 lunar months is a lunar year.
Among the Egyptians the month of thirty days each was in use long before the time of the Exodus, and formed the basis of their calculations. From the time of the institution of the Mosaic law the month among the Jews was lunar. The cycle of religious feasts depended on the moon. The commencement of a month was determined by the observation of the new moon. The number of months in the year was usually twelve (1 Kings 4:7; 1 Chr. 27:1-15); but every third year an additional month (ve-Adar) was inserted, so as to make the months coincide with the seasons. "The Hebrews and Phoenicians had no word for month save 'moon,' and only saved their calendar from becoming vague like that of the Moslems by the interpolation of an additional month. There is no evidence at all that they ever used a true solar year such as the Egyptians possessed. The latter had twelve months of thirty days and five epagomenac or odd days.", Palestine Quarterly, January 1889.