The Collaborative International Dictionary of English v.0.48:
musclebuilder \musclebuilder\ n. someone who does special exercises to develop the musculature; a bodybuilder. [WordNet 1.5]WordNet (r) 3.0 (2006):
musclebuilder n 1: someone who does special exercises to develop a brawny musculature [syn: bodybuilder, muscle builder, muscle- builder, musclebuilder, muscleman]