tendinous vs sinewy

tendinous and sinewy both are adjectives.

Word	Noun	Adjective	Verb	Adverb
tendinous	No	Yes	No	No
sinewy	No	Yes	No	No

As adjectives, tendinous and sinewy are synonyms defined as:

tendinous (adjective)	sinewy (adjective)
consisting of tendons or resembling a tendon	consisting of tendons or resembling a tendon
	(of a person) possessing physical strength and weight; rugged and powerful
	(of meat) full of sinews; especially impossible to chew