Islamic calendar

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The lunar calendar used by Muslims, reckoned from the year of the Hegira in AD 622.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• proper noun A calendar system deviding the year into twelve months.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun 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