Translation guide
Describes someone who is unwilling to speak, either because they are angry, determined, or secretive. The most natural Japanese expressions depend on the nuance: physical tightness of the mouth, emotional silence, or refusal to reveal information.
The person is silent because they are angry, stubborn, or resolute, often with a closed mouth.
Literally 'to tie one's mouth tightly'. Used when someone firmly shuts their mouth, often from anger or determination. Very visual and natural.
彼は口を固く結んで何も言わなかった。
He kept his mouth tightly shut and said nothing.
Means 'silent' or 'without words'. Can describe a tight-lipped attitude when combined with verbs like 押し通す (to persist).
彼女は無言を押し通した。
She remained tight-lipped the whole time.
To fall silent and refuse to speak, often with a stubborn or heavy atmosphere. Implies a deliberate silence.
彼は押し黙って窓の外を見ていた。
He sat tight-lipped, staring out the window.
The person is unwilling to share details, often in a situation like an interview or interrogation.
Literally 'mouth is hard'. A common idiom meaning someone is tight-lipped or discreet, good at keeping secrets.
彼は口が固いから、秘密を話しても大丈夫だ。
He's tight-lipped, so it's safe to tell him secrets.
Means 'won't say anything at all'. Used when someone completely refuses to comment, often in formal or news contexts.
警察は事件について一切語らなかった。
The police were tight-lipped about the incident.
Formal/legal term for 'remain silent' or 'refuse to answer'. Used in official contexts like police questioning.
容疑者は黙秘権を行使した。
The suspect exercised the right to remain silent.
Describing the actual appearance of lips pressed together, often from tension or anger.
Literally 'to tie one's lips tightly'. Describes the physical action of pressing lips together firmly.
彼女は唇を固く結んでうつむいた。
She looked down, her lips tight.
Describes the mouth area becoming tense or firm, often reflecting inner resolve or anger.
彼の口元が引き締まった。
His mouth set in a tight line.
口が固い describes a person's character (discreet, trustworthy). 口を固く結ぶ describes a temporary action or state (refusing to speak now).
彼は口が固い。
He is tight-lipped (by nature).
彼は口を固く結んだ。
He clamped his mouth shut (at that moment).