Synonyms and related words :
OK, accept, accredit, affirm, amen, and candle, approve, assert under oath, assure, attest, authenticate, authorize, autograph, book, certify, confirm, cosign, countersign, depone, depose, endorse, give permission, give the go-ahead, give the imprimatur, give thumbs up, guarantee, initial, kiss the book, notarize, pass, pass on, pass upon, permit, ratify, rubber stamp, sanction, say amen to, seal, second, sign, sign and seal, subscribe to, support, swear, swear and affirm, swear by bell, swear the truth, swear to God, swear to goodness, testify, undersign, underwrite, validate, visa, vise, vouch, vow, warrant