gnaw

gnaw is a   Verb

Definition:

[1] To bite, as something hard or tough, which is not readily separated or crushed; to bite off little by little, with effort; to wear or eat away by scraping or continuous biting with the teeth; to nibble at. His bones clean picked; his very bones they gnaw. Dryden.

[2] To bite in agony or rage. They gnawed their tongues for pain. Rev. xvi. 10.

[3] To corrode; to fret away; to waste.

Synonyms: