noun which may take the genitive case particle 'no'
Used as a no-adjective to describe documents, information, or matters that are meant to be kept secret or private. Common in business and formal contexts.
この書類はコンフィデンシャルですので、関係者以外には見せないでください。
This document is confidential, so please do not show it to anyone other than those involved.
コンフィデンシャルな情報を外部に漏らしてはいけません。
You must not leak confidential information to outsiders.