ROGET THESAURUS
word of honor
Promise
N
promise, undertaking, word, troth, plight, pledge, parole,
word of honor, vow, oath, profession, assurance, warranty, guarantee, insurance, obligation, contract, stipulation, engagement, preengagement, affiance, betroth, betrothal, betrothment, promising, promissory, votive, under hand and seal, upon oath, promised, affianced, pledged, bound, committed, compromised, in for it, as one's head shall answer for, in for a penny in for a pound, ex voto, gage d'amour.