THESAURUS
undersign
OK, accept, accredit, affirm, amen, approve, assure, attest, authenticate, authorize, autograph, back, be sponsor for, bond, certify, confirm, cosign, countersecure, countersign, endorse, ensure, give permission, give the go-ahead, give the imprimatur, give thumbs up, guarantee, guaranty, initial, insure, notarize, pass, pass on, pass upon, permit, ratify, rubber stamp, sanction, say amen to, seal, second, secure, sign, sign and seal, sign for, sponsor, stand behind, stand up for, subscribe to, support, swear and affirm, swear to, underwrite, validate, visa, vise, warrant
ROGET THESAURUS
undersign
Evidence
VB
be evidence, evince, show, betoken, tell of, indicate, imply, involve, argue, bespeak, breathe, have weight, carry weight, tell, speak volumes, speak for itself, rest upon, depend upon, repose on, bear witness, give evidence, testify, depose, witness, vouch for, sign, seal,
undersign, set one's hand and seal, sign and seal, deliver as one's act and deed, certify, attest, acknowledge, make absolute, confirm, prove (demonstrate), indorse, countersign, corroborate, support, ratify, bear out, uphold, warrant, adduce, attest, cite, quote, refer to, appeal to, call, call to witness, bring forward, bring into court, allege, plead, produce witnesses, confront witnesses, place into evidence, mark into evidence, collect evidence, bring together evidence, rake up evidence, experiment, have a case, make out a case, establish, authenticate, substantiate, verify, make good, quote chapter and verse, bring home to, bring to book.