IPA: /ˈoʊ.vərˌmʌs.əld/
KK: /ˈoʊvərˌmʌsəld/
Having an excessive amount of muscle or being overly muscular in appearance.
The bodybuilder was so overmuscled that he struggled to fit into regular clothes.
Overmuscled → It is formed from "over-" (meaning excessively) and "muscle" (from Latin "musculus", meaning little mouse or muscle). The word "overmuscled" means having excessively developed muscles.
Think of having muscles that are "excessive" or "over" what is normal — that's why overmuscled refers to someone with very large muscles.
No commonly confused words.