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