/ Thesaurus / T Synonyms of thirty first Find synonyms for: Adjective1. thirty-first, 31st, ordinal (vs. cardinal)usage: coming next after the thirtieth in positionWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: grimace Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language