What is Calendar Month?

Legal Definition
One of the months of the year as enumerated in the calendar, January, February, March, etc., without reference to the number of days it may con-tnin; as distinguished from a lunar month, of twenty-eight days, or a month for business purposes, which may contain thirty, at whatever part of the year it occurs. Daley v. Anderson. 7 Wyo. 1, 48 Pac. 840, 75 Am. St. Rep. 870; Migotti v. Co.Ivil, 4 C. P. Div. 233; In re Parker's Estate, 14 Wkly. Notes Cas. (Pa.) 566.
-- Black's Law Dictionary
Legal Definition
A period terminating with the day of the succeeding month numerically corresponding to the day of its beginning, less one. If there be no corresponding day, it terminates with the las-t day thereof. See 46 Neb. 427, 50 Am. St. Rep. 617, 30 L. R. A. 450, 65 N. W. 46.
-- Ballentine's Law Dictionary