/ Thesaurus / B Synonyms of brace up Find synonyms for: Verb1. undergird, brace up, strengthen, beef up, fortifyusage: make secure underneath; "undergird the ship"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: devout Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language