Dante Terrell Smith (born December 11, 1973), better known by his stage name Mos Def, is an acclaimed American MC and actor. Mos Def started his rap career as a member of the Native Tongue Posse collective and by guesting on albums by Da Bush Babees and De La Soul. He released a well-received album with Talib Kweli as Black Star, and was a major force in the late 1990s underground hip hop explosion spearheaded by Rawkus Records. His name does not have anything to do with the words 'most definitely,' which is often misrepresented as the reason for his stage name being Mos Def. Instead, Mos Def refers to his belief that he is in fact the most 'def' of all ('def' being the old school Hip Hop term for 'cool'). Although, he would later release a compilation album which makes reference to his named called Mos Definite.   Wikipedia