surety

1 a formal agreement to fulfill an obligation gave his surety that he would pay back the loan if his sister was unable to for any reason Synonyms bond, contract, covenant, deal, guaranty, guarantee, warrantyRelated Words oath, pledge, troth, vow, word; accord, bargain, compact, concordat, convention, pact, treaty; assurance, insurance, seal; bail, deposit, pawn, security

2 a person who takes the responsibility for some other person or thing a mutual friend agreed to act as surety if I lent my cousin some money, since I wasn't certain that she'd be able to pay it back Synonyms backer, guarantor, patron, sponsorRelated Words chaperone (or chaperon); advocate, champion, supporter; angel, benefactor, underwriter; coach, mentor, teacher; cosponsor; cosignatory, cosigner

3 a state of mind in which one is free from doubt I can't tell you the year in which that event happened with any great surety Synonyms assurance, assuredness, certainty, certitude, cocksureness, conviction, doubtlessness, face, positiveness, satisfaction, sureness, confidenceRelated Words authoritarianism, dogmatism; decisiveness, determination, firmness, purposefulness, resoluteness, resolution, resolveNear Antonyms hesitancy, hesitation, indecisiveness, irresolution; disbelief, incredulity, unbelief; anxiety, concern, misgiving; distrust, mistrust, suspicionAntonyms doubt, incertitude, nonconfidence, uncertainty