fit in vs blend

fit in is not a noun while blend is a noun.

Word	Noun	Adjective	Verb	Adverb
fit in	No	No	Yes	No
blend	Yes	No	Yes	No

As verbs, blend is a hyponym of fit in; that is, blend is a word with a more specific, narrower meaning than fit in:

Other hyponyms of fit in include coordinate, blend in, go.

fit in (noun)	blend (noun)
	the act of blending components together thoroughly
	a new word formed by joining two others and combining their meanings
	an occurrence of thorough mixing

fit in (verb)	blend (verb)
go together	mix together different elements
	combine into one
	blend or harmonize