Sinewy
Sinewy is an adjective used to describe a person, animal, or thing that displays a lean, muscular form with taut, well-developed tendons. In people, it implies strength, endurance, and agility rather than bulk alone; in descriptions of animals or labor-intensive contexts, it signals rugged resilience and readiness for strenuous activity. The term can also extend to nonhuman things that feel similarly tough and fibrous, such as textiles or fibers that are strong and elastic.
Etymology and nuance: Sinew refers to the connective tissue that links muscle to bone, and the adjective
Usage: In literature and journalism, sinewy appears most often in reference to bodies—athletes, fighters, or laborers—whose