Gnash /(?)/

Gnash

v. t.

imp. & p. p. Gnashed; p. pr. & vb. n. Gnashing

  1. To strike together, as in anger or pain; as, to gnash the teeth.

Gnash

v. i.
  1. To grind or strike the teeth together.
    There they him laid, Gnashing for anguish, and despite, and shame.