Synonyms for Guarantee:

n.

evince, declare, direct marketing, evidence, stand behind, aftermarket, endorse, call, attest, buyer's market, prove, cross-selling, support, detail, witness, answer for, credit rating, aver, churn rate, testify, customer care, cold call. company report, wager, pawn, blue book, charter, mortgage, confidentiality agreement, dossier, stake, concept statement, back, Consent Form, document, certificate, Annual Report. firm/safe ground, trust, certainty, confidence, gut feeling/instinct, surety, certitude, beyond any doubt, hunch. solemn word, give (someone) your word, vouchsafe, commit, word of honor, plight. stand up for, watch over, guard, save, keep (a) watch, shield, protect, defend, shelter. set off, form, make, bring about, invent, inaugurate, catalyze, start-off, trigger, create. borrowing power, creditworthiness, financier, borrowing, extension, creditworthy, compound interest, foreclose, debt collector, creditor. authorization (noun)
warrant.
certificate (noun)
certification.
communication (noun)
warranty, warrant, warrantee.
guarantee (noun)
warrantee, token, affirmation, vouch, oath, insurance, countersignature, guaranty, collateral, security, word, warranty, lien, contract, certification, assurance, undertake, warrant.
pledge, promise (noun)
guaranty, bond, covenant, certification, pawn, agreement, word of honor, certainty, surety, insurance, contract, warranty, word, vow, oath, undertaking, certificate, warrant, collateral, security, assurance, token, charter.
promise (noun)
mutual agreement, covenant, pact, agreement, obligation, engagement, arrangement, stipulation, understanding, compact.
promises (noun)
commitment.
word (noun)
word.
word of honor (noun)
pledge.

v.

communication (verb)
undertake, vouch.
guarantee (verb)
affirm, certify, warrant, assure, pledge, countersign, vouch, bond, safeguard, insure, ensure, secure, promise.
pledge, promise (verb)
wager, support, certify, evidence, insure, mortgage, prove, witness, affirm, evince, back, swear, assure, stake, aver, secure, answer for, attest, protect, stand behind, testify, stand up for, endorse, ensure.
promise (verb)
swear, vow, stipulate, agree, consent.

Other synonyms:

word of honor, solemn word, hunch, certainty, certitude. endorse, trust. confidence, defend. commit. declaration
certificate.
defend
stand up for.
promise
assure.
Other relevant words:
warrantee, certainty, pawn, word of honor, protect, certificate, witness, solemn word, shield, guaranty, surety, evidence, commit, commitment, answer for, guard, testify, shelter, endorse, declare, evince, trust, undertake, undertaking, defend, back, stand up for, stand behind, plight, mortgage, charter, wager, attest, support, aver, prove, stake, vouchsafe.

Usage examples for guarantee

  1. It was then about nine; he would guarantee that we should be there by twelve, at latest." – Tom Brown at Oxford by Thomas Hughes
  2. I offer you no guarantee you must use your judgment. – For the Allinson Honor by Harold Bindloss