The crossword solution for the term 'Actor/Rapper ___ Def' is MOS, which stands for 'Master of Speech'. Mos Def is an American actor and rapper who has been active in the entertainment industry since the late 1990s. He is best known for his roles in films such as The Italian Job, 16 Blocks, and Be Kind Rewind, as well as his music career, which includes five studio albums. He has also won several awards, including a Grammy Award for Best Rap Album in 2004.