IPA: /bɪˈtroʊðd/
KK: /bɪˈtroʊðd/
Having made a formal agreement to marry someone.
They are betrothed and planning their wedding for next year.
A person who is engaged to be married.
She introduced her betrothed to her family at dinner.
Betrothed is formed from "be-" (meaning to make or cause) and "troth" (from Old English "treowð", meaning faith or loyalty). The word describes the state of being made faithful or loyal to someone in a promise of marriage.
Think of being 'made' ('be-') faithful ('troth') to someone — that's what being betrothed means.