From Longman Dictionary of Contemporary Englishtop-secretˌtop-ˈsecret adjective SECRETtop-secret documents or information must be kept completely secret a top-secret code
Examples from the Corpus
top-secret• Huang was given a top-secret clearance at Commerce after what Republicans have called a lax background investigation.• top-secret government reports• If he does, it could be used by corporations, governments or any group that wanted to keep top-secret information secure.• Both had given away vast amounts of top-secret material without their employers being aware.• Evidence of MI6's involvement appeared in a top-secret report placed on the internet last month.• The men were carrying out top-secret research into radar, and until now the incident has been shrouded in mystery.• But at least he was out of his top-secret room and getting a bit of fresh air for a change.• The firm is described as a leading developer of top-secret weaponry. 