Heb harak, meaning "to grate the teeth", (Job 16:9; Ps 112:10; La 2:16), denotes rage or sorrow. (See also Ac 7:54; Mr 9:18.)
I am broken by his wrath, and his hate has gone after me; he has made his teeth sharp against me: my haters are looking on me with cruel eyes;
The sinner will see it with grief; he will be wasted away with envy; the desire of the evil-doers will come to nothing.
All your haters are opening their mouths wide against you; making hisses and whistling through their teeth, they say, We have made a meal of her: certainly this is the day we have been looking for; it has come, we have seen it.
And wherever it takes him, it puts him down violently, streaming at the lips and twisted with pain; and his strength goes from him; and I made a request to your disciples to send it out, and they were not able.
Hearing these things, they were cut to the heart and moved with wrath against him.
Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain