隠密[onmitsu] privacy
過密[kamitsu] overcrowding
確率密度関数[kakuritsumitsudokansuu] probability density function
機密[kimitsu] secrecy
機密性[kimitsusei] confidentiality

機密保護[kimitsuhogo] security (e.g. data, password, etc.)
気密[kimitsu] airtight
気密室[kimitsushitsu] airtight chamber
緊密[kinmitsu] rigour
軍事秘密[gunjihimitsu] military secret

秘露[peruu] Peru
極秘[gokuhi] absolute secrecy
軍事秘密[gunjihimitsu] military secret
厳秘[genpi] strict secret
公然の秘密[kouzennohimitsu] open secret

社外秘[shagaihi] company secret
神秘[shinpi] mystery
神秘学[shinhigaku] occultism (Western)
神秘的[shinpiteki] mysterious
秘める[himeru] to hide