口くちが堅かたい

expression, i-adjective

tight-lipped; able to keep a secret

Describes a person who does not reveal secrets or private matters. Often used positively to indicate trustworthiness.

See also: 口の堅い

Antonyms: 口が軽い

• 彼かれは口くちが堅かたいから、秘ひ密みつを話はなしても大だい丈じょう夫ぶだ。

  He is tight-lipped, so it's safe to tell him a secret.

• 口くちが堅かたい人ひとにだけこの情じょう報ほうを伝つたえてください。

  Please share this information only with people who can keep a secret.