/ Thesaurus / F Synonyms of flood plain Find synonyms for: Noun1. floodplain, flood plain, plain, field, champaignusage: a low plain adjacent to a river that is formed chiefly of river sediment and is subject to floodingWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language