To make sure or certain; convince or make confident, as by a promise, declaration, or other evidence: as, to assure a person of one's favor or love.To declare solemnly to; assert earnestly to; endeavor to convince by assertion: as, I assure you I am speaking the truth.To secure or confirm; make sure to be or to continue; give certainty or stability to: as, to assure a person's position or possessions.To free from obscurity, ambiguity, or uncertainty.To embolden; make confident.To affiance; betroth.To insure, as against loss.To confide; trust.To promise; pledge one's self.