bite down
verb1
To bite (something) very hard and usually for a purpose (like to hold it in one's mouth).
- Biting down on my wallet, I had two hands free to open the door.
2
To clench with one's teeth.
- He bit down to force himself not to say anything.
3
Figuratively To repress or bite back an (emotion, impulse or reaction).
- She bit down on the urge to strike the woman who had wronged her.