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.)
·vi To grind or strike the teeth together. II. Gnash ·vt To strike together, as in anger or pain; a...
Webster's Dictionary of the English Language