'top-secret' definitions:

Definition of 'top-secret'

adjective

The highest official level of classification of documents

From: GCIDE

classified \classified\ adj.
1. arranged into classes or categories; as, unclassified.
Syn: categorized. [WordNet 1.5 +PJC]
2. assigned to a class of documents withheld from general circulation; -- of information or documents. Opposite of unclassified.
Note: [Narrower terms: eyes-only; confidential; restricted; secret; sensitive; top-secret] [WordNet 1.5]