Breadcrumb Home > Thesaurus > O Synonyms of on that Find synonyms for: Adverb1. thereon, on it, on thatusage: on that; "text and commentary thereon"WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. ✖ Related Content Daily Word Quiz: triumphalism Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language