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.
この情報は秘密です。
This information is confidential.
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.
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.
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.
He kept the result a secret.
I promised to keep the secret between me and my friend.
She has a secret she can't tell anyone.
Everyone has at least one secret they keep.
秘密 is a general word for 'secret', while 極秘 stresses the highest, official level of confidentiality.
秘密 emphasizes deliberate confidentiality (a secret), whereas 非公開 simply means something is not made available to the public, without implying it must be hidden.
秘密 is the native Japanese word for 'secret' used in everyday speech, while シークレット is a loanword that adds a modern or stylish feel, often in compound nouns.
秘密 is a noun meaning 'a secret' or 'confidential matter', whereas 密か is an adjectival noun describing the manner in which something is done secretly.
秘密 is the general everyday word for 'secret', while 秘匿 is a formal term emphasizing the deliberate act of keeping something hidden.
in secrecy; behind closed doors
private key; secret key