1.
secret, confidential matter
Something that is kept hidden from others.
これは秘密だよ。
This is a secret.
秘密を守る。
To keep a secret.
秘密にしておいて。
Keep it a secret.
友達に秘密を打ち明けた。
I confided a secret to my friend.
二人だけの秘密にしようと約束したのに、みんなに知られてしまった。
We promised to keep it a secret between just the two of us, but everyone found out.
秘密 means a secret or confidential matter. It functions as a noun and can modify other nouns with の (秘密の場所, a secret place).
COMMON EXPRESSIONS:
- 秘密を守る: to keep a secret
- 秘密にする: to keep something secret
- 秘密を明かす: to reveal a secret
- 秘密を打ち明ける: to confide a secret
- 秘密を漏らす: to leak a secret
SIMILAR WORDS:
- ないしょ (内緒): casual word for secret, often used among friends and family
- 極秘: top secret, strictly confidential (formal/official)
NOTE:
秘密 is neutral in register and works in both casual and formal contexts. ないしょ is softer and more colloquial — ないしょにしてね is the casual equivalent of 秘密にしておいて.