muscular
/muskuˈlaɾ/ · B2 · verb
to build muscle mass by exercising
💪 muscular = músculo (muscle) + -ar, the verb ending: to muscle up
Spanish músculo comes from Latin musculus, 'little mouse', because a flexing bicep seems to scurry under the skin. Add the verb ending -ar and you get muscular: to build muscle. As an adjective it matches English 'muscular'.