guarantee

attest, authenticate, avouch, certify, testify (to), vouch (for), witness

assure, bond, contract, covenant

pledge, plight, stipulate, swear, undertake, vow

adhere, assert, aver, avow, declare, insist

insure

attest, certify, vouch, warrant, witness

pledge, promise, swear

advance, advertise, boost, plug, promote, publicize

announce, blaze, call, proclaim, pronounce, say

accent, accentuate, emphasize, stress, underline, underscore

advocate, champion, defend, espouse, support, uphold

assure, convince, persuade

explain, justify, rationalize

reaffirm, reassert

oath, pledge, troth, vow, word

accord, bargain, compact, concordat, convention, pact, treaty

assurance, insurance, seal

bail, deposit, pawn, security

bail, bond

deposit, down payment, earnest, handsel

surety, warranty

assurance, oath, promise, troth, word

commitment, compact, contract, covenant

recognizance