noun, noun or participle which takes 'suru', intransitive verb
Dated term for a firm oral promise or vow, often with a sense of sealing one's word. Modern Japanese more commonly uses 約束 or 誓い.
昔の武士は口固めを重んじた。
Samurai of old valued verbal promises.
口固めをして、必ず戻ると誓った。
He made a verbal pledge and swore he would definitely return.
noun, noun or participle which takes 'suru', intransitive verb
forbidding someone from telling others; swearing to secrecy
Dated term for making someone promise not to disclose something; akin to a gag order or confidentiality pledge. Often used in historical or dramatic contexts.
密談の前に、全員に口固めをした。
Before the secret talk, he made everyone swear to secrecy.
口固めがなければ、この話は外に漏れていただろう。
Without the gag order, this story would have leaked out.