legs vs toughness

legs and toughness both are nouns.

Word	Noun	Adjective	Verb	Adverb
legs	Yes	No	No	No
toughness	Yes	No	No	No

As nouns, toughness is a hypernym of legs; that is, toughness is a word with a broader meaning than legs:

Other hypernyms of legs include stamina, staying power.

legs (noun)	toughness (noun)
staying power	the property of being big and strong
	enduring strength and energy
	impressive difficulty
	the elasticity and hardness of a metal object; its ability to absorb considerable energy before cracking