mohammedan calendar

GNU Webster's 1913

1. A lunar calendar reckoning from the year of the hegira (hejira), 622 a. d. Thirty of its years constitute a cycle, of which the 2d, 5th, 7th, 10th, 13th, 16th, 18th, 21st, 24th, 26th, and 29th are leap years, having 355 days; the others are common, having 354 days.

WordNet 3.0

1. n. the lunar calendar used by Muslims; dates from 622 AD (the year of the Hegira); the beginning of the Muslim year retrogresses through the solar year completing the cycle every 32 years