I. ˈ ̷ ̷ˌ ̷ ̷ noun
Etymology: Middle English trouth plight, from trouth troth + plight
archaic : a solemn pledge usually to enter into the married estate
II. transitive verb
Etymology: Middle English trouth plighten, from trouth troth + plighten to pledge — more at plight
archaic : betroth