noun, na-adjective, noun which may take the genitive case particle 'no'
Core meaning: something kept hidden from others, or the state of being secret. Used as a noun and with な/の to modify nouns.
彼は私に秘密を打ち明けた。
He confided a secret to me.
この情
This information is confidential.
noun
Refers to something unknown or unexplained, often with a sense of wonder. Overlaps with sense 1 but emphasizes the unknown rather than deliberate concealment.
宇宙の秘密を解き明かす。
Unravel the mysteries of the universe.
noun
secret (to success, etc.); key
Used for a crucial, often non-obvious factor or method that leads to a desired result. Similar to 秘訣 (ひけつ).
See also: 秘訣
成功の秘密は努力を続けることだ。
The secret to success is to keep making efforts.
noun
esoteric teachings
Buddhist term for teachings transmitted secretly or only to initiates. Rare outside specialized contexts.
密教では秘密の教えが師から弟子へ伝えられる。
In esoteric Buddhism, secret teachings are passed from master to disciple.