To grit your teeth is to clench the jaw against pain or anger. Grit your teeth and get on with it.
It is used far more about enduring something than about the jaw. To grit your teeth through a task is to finish it without complaining about it.
1phrasegrit your teethTo clench the jaw against pain or anger.
“Grit your teeth and the injection is over in a second.”
grit your teeth is a gesture.
Practised in Body Language & Gestures