Wordnet 3.0
NOUN (1)
1. 
 the activity of making clear or converting from code into plain text; 
- Example: "a secret key or password is required for decryption"[syn: decoding, decryption, decipherment]
The Collaborative International Dictionary of English v.0.48:
Decipherment \De*ci"pher*ment\, n.
   The act of deciphering.
   [1913 Webster]
WordNet (r) 3.0 (2006):
decipherment
    n 1: the activity of making clear or converting from code into
         plain text; "a secret key or password is required for
         decryption" [syn: decoding, decryption, decipherment]