Month n.  One of the twelve portions into which the year is divided; the twelfth part of a year, corresponding nearly to the length of a synodic revolution of the moon, -- whence the name.  In popular use, a period of four weeks is often called a month.
 Note: ☞ In the common law, a month is a lunar month, or twenty-eight days, unless otherwise expressed. --Blackstone. In the United States the rule of the common law is generally changed, and a month is declared to mean a calendar month. --Cooley's Blackstone.
 A month mind. (a) A strong or abnormal desire. [Obs.] --Shak. (b) A celebration made in remembrance of a deceased person a month after death. --Strype.
 Calendar months, the months as adjusted in the common or Gregorian calendar; April, June, September, and November, containing 30 days, and the rest 31, except February, which, in common years, has 28, and in leap years 29.
 Lunar month, the period of one revolution of the moon, particularly a synodical revolution; but several kinds are distinguished, as the synodical month, or period from one new moon to the next, in mean length 29 d. 12 h. 44 m. 2.87 s.; the nodical month, or time of revolution from one node to the same again, in length 27 d. 5 h. 5 m. 36 s.; the sidereal, or time of revolution from a star to the same again, equal to 27 d. 7 h. 43 m. 11.5 s.; the anomalistic, or time of revolution from perigee to perigee again, in length 27 d. 13 h. 18 m. 37.4 s.; and the tropical, or time of passing from any point of the ecliptic to the same again, equal to 27 d. 7 h. 43 m. 4.7 s.
 Solar month, the time in which the sun passes through one sign of the zodiac, in mean length 30 d. 10 h. 29 m. 4.1 s.

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