/ 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: ontiguous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language