affiance

(əˈfaɪəns

)

verb

1 (transitive) to bind (a person or oneself) in a promise of marriage; betroth

▷ noun

2 archaic a solemn pledge, esp a marriage contract

[C14: via Old French from Medieval Latin affīdāre to trust (oneself) to, from fīdāre to trust, from fīdus faithful]

affianced