Note:  Do not rely on this information. It is very old.

Month

Month, originally (and when described as lunar) the interval between one new moon and the next, containing 29-530589 days. A solar month is the twelfth part of the solar year, containing 30-43685 days. A calendar month is one of the twelve divisions of the civil or calendar year, of which April, June, September, and November contain 30 days, February 28 (in leap year 29) days, the rest 31 days. Astronomers also use the terms anomalistic month, dracontic or nodical month, sidereal month, and tropical month, all with respect to revolution of the moon about the earth.