/ Thesaurus / P Synonyms of plump up Find synonyms for: Verb1. fluff up, plump up, shake up, shake, agitateusage: make fuller by shaking; "fluff up the pillows"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language