"Muscle," of course, can mean "strength," and so can "sinew," a word for the tissue that ties muscle to bone - more commonly known as a tendon. (For a while, "sinew" also meant "nerve," but that usage is obsolete.)

Is sinew and tendon the same thing?

'Tendon' is what we call it when it's in the body; living tissue – like the 'Achilles' Tendon. 'Sinew' is when we take that tendon, dry it, and process it into tiny fibers for use as cordage/string, etc.

Is a sinew a ligament?

As nouns the difference between ligament and sinew

is that ligament is (anatomy) a band of strong tissue that connects bones to other bones while sinew is (anatomy) a cord or tendon of the body.