grind (one's) teeth(redirected from grinding their teeth)
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.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
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.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012