The Collaborative International Dictionary of English v.0.48:

Decipher \De*ci"pher\, v. t. [imp. & p. p. Deciphered; p. pr.
   & vb. n. Deciphering.] [Pref. de- + cipher. Formed in
   imitation of F. d['e]chiffrer. See Cipher.]
   1. To translate from secret characters or ciphers into
      intelligible terms; as, to decipher a letter written in
      secret characters.
      [1913 Webster]

   2. To find out, so as to be able to make known the meaning
      of; to make out or read, as words badly written or partly
      obliterated; to detect; to reveal; to unfold.
      [1913 Webster]

   3. To stamp; to detect; to discover. [R.]
      [1913 Webster]

            You are both deciphered, . . .
            For villains.                         --Shak.
      [1913 Webster]