slang A large, muscular, oafish, typically unintelligent or foolish person, especially a man. Sometimes used endearingly or in self-deprecation. Some musclehead at the bar has been hitting on Jenny for the last 20 minutes—I'm going to go help her get out of there. A musclehead like me would never have a chance of getting into Yale! A football camp? No thank you—spending a week with two-dozen muscleheads does not sound like a fun time.