IPA: //bɪˈtreɪər//
KK: /bɪˈtreɪər/
A person who is disloyal or unfaithful, especially by revealing secrets or betraying trust.
He was labeled a betrayer after he shared confidential information with the enemy.
Betrayer → It is formed from "be-" (meaning about or around) and "traitor" (from Latin "traditor", meaning one who hands over or delivers). The word "betrayer" refers to someone who hands over trust or loyalty, often in a treacherous manner.
Think of someone who is 'around' ('be-') and 'hands over' ('traditor') trust — that's why a betrayer is someone who betrays trust.