fight vs fight off

fight is a noun but fight off is not a noun.

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

As verbs, fight off is a hyponym of fight; that is, fight off is a word with a more specific, narrower meaning than fight:

fight (noun)	fight off (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

fight (verb)	fight off (verb)
be engaged in a fight; carry on a fight	force or drive back
fight against or resist strongly
make a strenuous or labored effort
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