Grade 0 gnashing Get Printable Handwriting Hear It! Say It! Write It! Learn It! Spelling Test Definition verb. to grind or strike the teeth together, often in anger. Example Sentence The dog was gnashing his teeth at us. More Example Sentences The dog was gnashing its teeth at strangers. Synonyms grinding; clenching; biting Antonyms smile; relax Hear It! Say It! Write It! gnashing Switch to cursive Start Share with your friends: