/ Thesaurus / 4 Synonyms of 400 Find synonyms for: Adjective1. four hundred, 400, cd, cardinal (vs. ordinal)usage: being one hundred more than three hundredWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: acerbity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language