THIS PSAT VOCABULARY QUIZ IS PERFECT PRACTICE FOR THE REAL TEST
Words nearby knuckle down
Idioms and Phrases with knuckle down
Apply oneself seriously to some task or goal, as in The professor insisted that we knuckle down and get our papers in by Friday. Both this term and the rhyming synonym buckle down date from the 1860s, but the precise allusion in either is unclear.
See knuckle under.