noun
Used in formal, business, or technical contexts to describe the property of information being kept secret or restricted.
この書類は機密性が高いので、取り扱いに注意してください。
This document has high confidentiality, so please handle it with care.
情報の機密性を守るために、パスワードを
To maintain the confidentiality of information, we change passwords regularly.
機密 means 'secret' or 'classified information', whereas 機密性 is the abstract noun meaning 'confidentiality' or the property of being secret.
Compound of 機密 (secret, classified) and 性 (nature, property). The word is a modern Sino-Japanese formation used in business and legal contexts.