'Gnash' in the Bible

The wicked plots against the righteousAnd gnashes at him with his teeth.

The wicked will see it and be angered,He will gnash his teeth and melt away [in despair and death];The desire of the wicked will perish and come to nothing.

All your enemiesHave opened their mouths wide against you;They [scornfully] hiss and gnash their teeth.They say, “We have swallowed her up!Certainly this is the day for which we waited;We have reached it, we have seen it!”