Synonyms for Niagara (same or very similar meaning)
WordNet sense 1 (waterfall in Canada is the Horseshoe Falls; in the United States it is the American Falls):
Niagara FallsWordNet sense 2 (a river flowing from Lake Erie into Lake Ontario; forms boundary between Ontario and New York):
Niagara RiverFrom the ODE community, based on WordNetadd/edit