defend vs fight

defend is not a noun while fight is a noun.

Word	Noun	Adjective	Verb	Adverb
defend	No	No	Yes	No
fight	Yes	No	Yes	No

As verbs, defend and fight are synonyms defined as:

Other synonyms of defend include fight back, fight down, oppose.

As verbs, fight is a hypernym of defend; that is, fight is a word with a broader meaning than defend:

Other hypernyms of defend include contend, struggle.

defend (noun)	fight (noun)
	a hostile meeting of opposing military forces in the course of a war
	the act of fighting; any contest or struggle
	a boxing or wrestling match
	an aggressive willingness to compete
	an intense verbal dispute

defend (verb)	fight (verb)
argue or speak in defense of	be engaged in a fight; carry on a fight
state or assert	fight against or resist strongly
be on the defensive; act against an attack	make a strenuous or labored effort
protect against a challenge or attack	exert oneself continuously, vigorously, or obtrusively to gain an end or engage in a crusade for a certain cause or person; be an advocate for
protect or fight for as a champion
fight against or resist strongly
be the defense counsel for someone in a trial