This is the 13182nd most frequent Swedish word.
topphemliga
"Top secret."
The word 'topphemliga' is used here as an adjective describing 'dokumenten', meaning that the documents are of the highest confidentiality level.
De diskuterade de topphemliga dokumenten under mötet.
They discussed the top-secret documents during the meeting.
In this sentence, 'topphemligt' is used as an adjective modifying 'projekt', indicating that the project is highly confidential.
Han arbetar på ett topphemligt projekt som inte kan delas med någon.
He is working on a top-secret project that cannot be shared with anyone.
Here, 'topphemlig' is an adjective qualifying 'informationen', emphasizing the secrecy level of the information.