ROGET THESAURUS
promissory
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.