know-it-all vs egoist

know-it-all and egoist both are nouns.

Word	Noun	Adjective	Verb	Adverb
know-it-all	Yes	No	No	No
egoist	Yes	No	No	No

As nouns, egoist is a hypernym of know-it-all; that is, egoist is a word with a broader meaning than know-it-all:

know-it-all: someone who thinks he knows everything and refuses to accept advice or information from others
egoist: a conceited and self-centered person

Other hypernyms of know-it-all include egotist, swellhead.

know-it-all (noun)	egoist (noun)
someone who thinks he knows everything and refuses to accept advice or information from others	a self-centered person with little regard for others
	a conceited and self-centered person