Synonyms and related words :
OK, X, acceptance, affirmance, affirmation, approbation, approval, authentication, authorization, autograph, certification, christcross, cipher, confirmation, countermark, countersign, countersignature, counterstamp, cross, device, endorsement, go-ahead, green light, hand, imprimatur, initials, mark, mark of signature, monogram, nod, notarization, okay, permission, ratification, rubber stamp, sanction, seal, sigil, sign manual, signature, signet, stamp, stamp of approval, subscription, the nod, validation, visa, vise, warrant