'Gnashing' in the Bible

But the children of the kingdom shall be cast out into outer darkness: there shall be weeping and gnashing of teeth.

And shall cast them into a furnace of fire: there shall be wailing and gnashing of teeth.

And shall cast them into the furnace of fire: there shall be wailing and gnashing of teeth.

Then said the king to the servants, Bind him hand and foot, and take him away, and cast him into outer darkness; there shall be weeping and gnashing of teeth.

And shall cut him asunder, and appoint him his portion with the hypocrites: there shall be weeping and gnashing of teeth.

And cast ye the unprofitable servant into outer darkness: there shall be weeping and gnashing of teeth.