Source : Webster's Revised Unabridged Dictionary (1913)

Mohammedan calendar \Mo*ham"med*an cal"en*dar\
   A lunar calendar reckoning from the year of the hegira, 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.

   Note: By the following tables any Mohammedan date may be
         changed into the Christian date, or vice versa, for the
         years 1900-1935 a. d.

Source : WordNet®

Mohammedan calendar
     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 [syn: {Islamic calendar}, {Muhammadan
         calendar}, {Moslem calendar}, {Muslim calendar}]