noun, na-adjective, noun which may take the genitive case particle 'no'
privacy; secrecy; confidentiality
Used for matters kept private or secret, often in formal or business contexts. Can be used as a noun or adjectivally with な or の.
Please keep this matter confidential.
Confidential information was leaked.
内密 describes something kept confidential within a limited circle, whereas 隠密 emphasizes stealthy, undetected execution.
内密 describes doing something quietly and privately between a few people, while 極秘 implies an official, top-level classification of secrecy.
内密 refers to keeping something quietly private between a few people, while 機密 refers to formally classified organizational or state secrets.
Compound of 内 (inside, internal) and 密 (secret, dense). The exact historical derivation is uncertain, but the combination naturally conveys 'internal secrecy'.