mesomorph

This term originates from somatotyping, a system used to categorize human physiques. It describes a body type that is naturally athletic and muscular, typically possessing a broad shoulder-to-hip ratio and a lean waist. In modern usage, it is frequently employed in fitness, bodybuilding, and sports science to describe individuals who respond quickly to strength training.

While the term is used as a technical classification, it is often applied colloquially to describe someone who looks "naturally fit" or "built." It is distinct from an ectomorph (lean and slender) and an endomorph (heavier with a tendency to store fat).