Involuntary grinding or clenching of the teeth (often during sleep); medically known as bruxism and can damage teeth or jaws.
彼は寝ている間に歯ぎしりをしていると奥さんに言われた。
His wife told him he grinds his teeth while sleeping.
ストレスで歯ぎしりがひどくなり、歯が削れてしまった。
Stress worsened my teeth grinding, and my teeth got worn down.
歯ぎしりを防ぐためのマウスピースを歯科で作ってもらった。
I had a mouthguard made at the dentist to prevent teeth grinding.
Grinding one's teeth out of anger or vexation — a behavioral expression of strong emotion.
彼女は怒りで歯ぎしりしながら席を立った。
She stood up, grinding her teeth in anger.
上司の無理解に歯ぎしりしそうになったが、こらえた。
I almost ground my teeth at my boss's lack of understanding, but I held back.