'Gnash' in the Bible

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

The wicked shall see it, and be grieved; he shall gnash with his teeth, and melt away: the desire of the wicked shall perish.

All thine enemies have opened their mouth against thee: they hiss and gnash the teeth: they say, We have swallowed her up: certainly this is the day that we looked for; we have found, we have seen it.