Definition from Wiktionary, the free dictionary
Alternative forms 
- (Islam) The pilgrimage to Mecca made by pious Muslims; one of the five pillars
- 1855: The word Hajj is explained by Moslem divines to mean “Kasd,” or aspiration, and to express man’s sentiment that he is but a wayfarer on earth wending towards another and a nobler world. — Sir Richard Francis Burton, Personal Narrative of a Pilgrimage to Al-Madinah & Meccah, 1855, Appendix I.
Derived terms 
pilgrimage to Mecca