If something is sinewy, it has a lot of strong, tough tissue that connects muscles to bones.
Sinewy can make people think of strength, toughness, and hard work.
Examples:
The lion had a sinewy body.
Her arms were sinewy from all the hard work.
The sinewy rope held the heavy weight.
The sinewy tree branches were hard to break.
The sinewy wrestler could lift heavy things easily.
The sinewy dog pulled the cart up the hill.