Breadcrumb Home > Thesaurus > O Synonyms of ontario Find synonyms for: Noun 1. Lake Ontario, Ontario usage: the smallest of the Great Lakes 2. Ontario usage: a prosperous and industrialized province in central Canada WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.Definition and meaning of ontario (Dictionary) TrendingHere are the facts and trivia that people are buzzing about. Biographies: Notable Jewish Religious Leaders Current Events This Week: September 2023 Hispanic Population and the 2010 U.S. Census Preamble of the United Nations Charter The Jewish Calendar ✖ Related Content Daily Word Quiz: oblique Analogy of the Day: Today’s Analogy Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language