grind (one's) teeth

To internalize one's anger without expressing it externally. The image is that of a person literally grinding their teeth together out of anger. Don't just sit there, grinding your teeth—if you're mad at me, let's talk about it. All I've gotten are a few passive-aggressive comments, so Mom is definitely grinding her teeth about something. Our marriage counselor has advised us not to grind our teeth when we're unhappy with each other. "Communication is key," he says.

grind your teeth

If someone grinds their teeth, they are angry about something, but do not express their anger. We journalists, who once were just like him, grind our teeth as we contemplate his success. Note: You can also talk about grinding of teeth, teeth-grinding, and tooth-grinding. There has been much grinding of teeth about what is seen by the government as the harshness of the European Community's decisions. When you are a little boy of nine, your father can seem like a hero one minute, only to cause you tooth-grinding embarrassment the next.