also: ないしょうごと
secret; private matter; confidential matter
Refers to something kept secret or private, often among a small group. Commonly used in phrases like 内緒事にする (to keep something secret).
This is a secret just between the two of us.
You must not leak the company's confidential matters to outsiders.
秘密 is a more general and formal word for 'secret', while 内緒事 often implies a personal or informal secret kept within a close circle.
内緒 is a noun meaning 'secrecy' or 'keeping something secret', often used in the phrase 内緒にする. 内緒事 specifically refers to the secret matter itself.
Standard kanji spelling for this word.
Mixed kanji-kana spelling; common in everyday writing.
Rarely used kanji form with the reading ないしょうごと.
Compound of 内緒 (ないしょ, 'secrecy') and 事 (こと, 'matter'). The kanji 内証 is an alternative spelling for 内緒, but 内証事 is rare.