know-it-all

English Thesaurus

1. someone who thinks he knows everything and refuses to accept advice or information from others (noun.person)

hypernym	:	egoist, egotist, swellhead,
definition	:	a conceited and self-centered person (noun.person)

domain usage	:	colloquialism,
definition	:	a colloquial expression; characteristic of spoken or written communication that seeks to imitate informal speech (noun.communication)