The term "musclebound" refers to someone who is overly muscular and lacks flexibility. If you're looking for synonyms for this word, you might consider "rigid," "inflexible," or "stiff." Other possible options include "unyielding," "tense," or "tightly wound." Additionally, you could use terms like "bulky," "thickset," or "heavyset" to describe someone who is muscular but lacks agility or range of motion. Ultimately, the best synonym for "musclebound" will depend on the particular context in which it is being used and the specific connotations that you want to convey.