Wordnet 3.0
VERB (1)
1. 
 lift the restriction on and make available again; 
- Example: "reclassify the documents"
The Collaborative International Dictionary of English v.0.48:
declassify \declassify\ v.
   to lift the restriction on publication [of documents] by
   reducing or eliminating the secrecy classification of; --
   usually applied to government documents classified as secret.
   Syn: make available again.
        [WordNet 1.5]
WordNet (r) 3.0 (2006):
declassify
    v 1: lift the restriction on and make available again;
         "reclassify the documents" [ant: classify]