adjective
Definition: Describing a body type that is thin and lacks muscle, or relating to a state of weakness or lack of energy.
Example: The athlete had an asthenic build, which made him appear more fragile than his competitors.
noun
Definition: A person who has a thin and weak body structure, often characterized by a lack of muscle and fat.
Example: The asthenic individual struggled to keep up with the more athletic members of the team.