WordNet (r) 3.0 (2006):

notarize
    v 1: authenticate as a notary; "We had to have the signature
         notarized" [syn: notarize, notarise]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "notarize":
   OK, accept, accredit, affirm, amen, approve, authenticate,
   authorize, autograph, certify, confirm, cosign, countersign,
   endorse, give permission, give the go-ahead, give the imprimatur,
   give thumbs up, initial, pass, pass on, pass upon, permit, ratify,
   rubber stamp, sanction, say amen to, seal, second, sign,
   sign and seal, subscribe to, support, swear and affirm, swear to,
   undersign, underwrite, validate, visa, vise, warrant