Source : WordNet®

decryption
     n : the activity of making clear or converting from code into
         plain text; "a secret key or password is required for
         decryption" [syn: {decoding}, {decipherment}]

Source : Free On-Line Dictionary of Computing

decryption
     
         Any procedure used in {cryptography} to convert
        {ciphertext} (encrypted data) into {plaintext}.
     
        (1995-05-10)