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.)
He is angry at me, he hateth me, and gnasheth upon me with his teeth. Mine enemy scowleth upon me with his eyes.
The ungodly shall see it, and it shall grieve him; he shall gnash with his teeth, and consume away, and the desire of the ungodly shall perish.
{Ayin} All thine enemies gape upon thee, whispering and biting their teeth, saying, "Let us devour, for the time that we looked for is come: we have found and seen it."
And whensoever he taketh him, he teareth him, and he foameth, and gnasheth with his teeth, and pineth away. And I spake to thy disciples that they should cast him out, and they could not."
When they heard these things, their hearts clave asunder, and they gnashed on him with their teeth.