Synonyms for Warrant:

n.

motivation, in justification of something, ground, occasion, motive, pretext, cause, point. basis, true, working papers, reason, licence, foundation, card, justification, building permit. evidence, commit, proof, swear, testimony, give (someone) your word, vouchsafe, corroboration, attestation, substantiation, demonstration, testimonial, verification, testament. chevron, body armor, cruiser, earnest, token, flak jacket, Denver boot, boot, baton, cuffs, breathalyzer, security, billy club, pawn. start-off, surety, catalyze, inaugurate, make, obligation, trigger, set off, form, bring about, invent, create. engagement, solemn word, covenant, vow, plight, word of honor, assurance, word. allow, law. authorization (noun)
approval, empowerment, guarantee, certificate, permit, agreement, entitlement, designation, word, commission, pawn, warranty, certification, pass, enfranchisement, foundation, credentials, testimonial, affirmation, authentication, verification, sanction, authorization, official document, permission, summons, notarization, blessing, pledge, subpoena, validation, credential, token, license, basis, confirmation, passport, assurance, earnest, security.
certificate (noun)
certification.
evidence (noun)
proof.
permit (noun)
permit.
promise (noun)
solemn word.
warrant (noun)
imprimatur, stock warrant, justify, endorsement, countenance, warranty, sanction, stock-purchase warrant, warrantee, guarantee.
word (noun)
word.
word of honor (noun)
pledge.

v.

affirm (verb)
ratify, affirm, admit, assert, maintain, state, corroborate, endorse, pledge, approve, submit, claim, sustain, proclaim, validate, pronounce, profess, declare, assure, contend, adjure, attest, aver, set down, acknowledge, avouch, certify, verify, propound, testify, support, promise, express, accept.
authorize (verb)
license, authorize, empower, consent, authenticate, notarize, countersign, assent, sanction, designate, enfranchise, permit, commission, deputize, ordain, denominate, confirm, enable, entitle, agree, bless.
communication (verb)
guarantee.
deserve (verb)
deserve, merit.
guarantee (verb)
secure, bond, vouch, safeguard, insure, guarantee, ensure.
guarantee, justify, authorize (verb)
promise, assure, ensure, claim, assert, secure, contend, approve, vow, endorse, insure, swear, avouch, empower, state, declare, certify, entitle, maintain, affirm, attest.

Other synonyms:

building permit, summons, corroboration, attestation, allow, solemn word, law, word of honor, working papers, basis. verification, evidence, vow, testimonial, testament, swear, substantiation. pawn, assurance, testimony. demonstration, covenant, token. engagement. reason, security. word. foundation. card. pass. declaration
certificate.
empower
empower.
excuse
justification.
identification
passport.
justify
justify.
summons
subpoena.
Other relevant words:
demonstration, trigger, covenant, commit, law, justify, obligation, countenance, endorsement, building permit, occasion, inaugurate, stock warrant, breathalyzer, testimonial, boot, foundation, engagement, cuffs, surety, chit, token, create, passport, vow, stock-purchase warrant, pawn, invent, verification, official document, proof, testimony, swear, pass, motive, assurance, motivation, summons, attestation, cause, baton, certificate, true, warranty, allow, chevron, solemn word, card, catalyze, pretext, subpoena, vouchsafe, imprimatur, credential, credentials, ground, make, point, testament, reason, earnest, basis, word, corroboration, cruiser, form, evidence, plight, warrantee, justification, word of honor, licence, security, substantiation.

Usage examples for warrant

  1. As a matter of fact, the search warrant would have met the difficulty. – The Grell Mystery by Frank Froest
  2. My dear Fanny- Still I cannot afford to spend money by Coachhire and still my throat is not well enough to warrant my walking. – Letters of John Keats to His Family and Friends by John Keats