classified
adjective
Definitions
Sorted into classes or categories
Formally assigned by a government to one of several levels of sensitivity, usually (in English) top secret, secret, confidential, and, in some countries, restricted; thereby making disclosure to unauthorized persons illegal.
Example: We do not discuss specific interrogation techniques because they are classified information.
Not meant to be disclosed by a person or organization.
verb
Definitions
To identify by or divide into classes; to categorize
Example: Should we classify "make up" as an idiom or as a phrasal verb?
To declare something a secret, especially a government secret
Example: They decided to classify that information.