/ Thesaurus / C Synonyms of coastal plain Find synonyms for: Noun1. coastal plain, land, dry land, earth, ground, solid ground, terra firmausage: a plain adjacent to a coastWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: knead Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language