隠密|おんみつonmitsu[0]heiban (flat)

1. na-adjective, no-adjectivesecret; clandestine; covert; stealthy
2. nounspy (for a daimyo, shogun, etc.); secret agent

• Synonym秘密ひみつNeutralNeutral and most general: a hidden thing or keeping secrets, also mysteries and tricks. 「隠密」 stresses covert action and can mean an Edo-period spy.
• Related非公開ひこうかいWrittenWritten/formal: means not open to the public, typical of meetings, documents and information. 「隠密」 describes covert action and can also mean a spy.
• Related内々うちうちNeutralNeutral: private handling among insiders only, as in 「内々に進める」; common in business. 「隠密」 stresses covert action hidden from outsiders.
• Related内密ないみつWrittenWritten/formal: keeping something confidential, as in 「内密に願います」; the point is not letting it be known. 「隠密」 stresses covert action or a spy.
• Related内緒ないしょCasualColloquial everyday word for keeping something secret, as in 「内緒にしてね」. 「隠密」 is more written and evokes covert action or spies.
• Related秘め事ひめごとWrittenWritten/formal: the hidden matter itself, often with a romantic or illicit flavor. 「隠密」 describes the covert manner of acting, not the thing.
• Antonym公開こうかいWrittenWritten/formal antonym: making something public or open, as in 「情報を公開する」 — the opposite of acting covertly as 「隠密」 does.
• Antonym表立つおもてだつNeutralNeutral antonym: coming out into the open or taking official form, as in 「表立って反対する」 — the opposite of 「隠密」's covert action.

For general secrets use 「秘密」, colloquially 「内緒」; for not making something public use 「非公開」. 「隠密」 is for covert, under-the-table action, as in 「隠密行動」, and can also mean an Edo-period spy.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 密ひそかに何なんかをすること。秘密ひみつ。
2. 間者かんじゃ。スパイ。しのび。