the lunar calendar used by Muslims and reckoned froma.d.622: the calendar year consists of 354 days and contains 12 months: Moharram, Safar, Rabi I, Rabi II, Jumada I, Jumada II, Rajab, Shaban, Ramadan, Shawwal, Dhu 'l-Qa"da, and Dhu 'l-hijjah. In leap years the month Dhu 'l-hijjah contains one extra day. Also called Islamic calendar. See table under calendar.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.