Gnash
Gnash , transitive verb
[Old English gnasten, gnaisten, compare Icelandic gnastan a gnashing, gn{not transcribed}sta to gnash, Danishknaske, Swedish gnissla, Dutch knarsen, German knirschen.]
To strike together, as in anger or pain; as, to gnash the teeth.
Gnash , intransitive verb
To grind or strike the teeth together.
There they him laid,
Gnashing for anguish, and despite, and shame.