classified information

Information whose unauthorised disclosure would or could cause damage to the Republic of Poland, or would be detrimental from the point of view of its interests.

The rules for protecting such information are set out in the Act on the Protection of Classified Information (Article 1(1)).¹

In CIA terminology, the equivalent is classified information, whose disclosure could harm national security and to which access is limited to people with a clearance and a need to know.²