Gnash

Heb. harak, meaning “to grate the teeth”, (Job 16:9; Ps. 112:10; Lam. 2:16), denotes rage or sorrow. (See also Acts 7:54; Mark 9:18.)

GNASH, GNASH'ING, a striking or grinding of the teeth in the paroxysms of anguish or despair. Ps 112:10;Matt 8:12.

Part of speech: verb (v.)

To strike together, as in anger or pain; as, to gnash the teeth.

Part of speech: verb (v.)

To grind or strike the teeth together. There they him laid, Gnashing for anguish, and despite, and shame. Milton.