/ Thesaurus / B Synonyms of buckle down Find synonyms for: Verb1. slave, break one's back, buckle down, knuckle down, work, do workusage: work very hard, like a slaveWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: reticent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language