The word 'gnash' originally came from Scandinavian as 'gnastan'

'Gnash' is a word borrowed from Scandinavian 'gnastan'. The word entered the English language some time around the 15th century.

gnash [verb] [15th century]

To strike or grind (as the teeth) together

See 'gnash' on the Loan Words Map

See more loan words from Scandinavian.

note: Old Norse gnastan gnashing of teeth
Etymology: Alteration of Middle English 'gnasten'

See more loan words from 1400s.