[1] : The Collaborative International Dictionary of English v.0.48

unseal \unseal"\ u^ns=el", v. t. 1st pref. un- + seal.
   1. to break or remove the seal of; to open, as what is
      sealed; as, to unseal a letter.
      1913 webster

            unable to unseal his lips beyond the width of a
            quarter of an inch.                   --sir w.
                                                  scott.
      1913 webster

   2. to disclose, as a secret. obs. --the coronation.
      1913 webster

[2] : WordNet (r) 2.0

unseal
     v : break the seal of; "he unsealed the letter" ant: seal
see also:
seal 

Unseal >> U Words
Unseal, definition of term: Unseal
unseal_pag1.html