niagara niacin • Niagara · · · Info · Definitions · Characters · · niagara · · Text Latin · · Script 7 · · Length 4 · · Syllables Definitions · · · (noun) waterfall in Canada is the Horseshoe Falls; in the United States it is the American Falls. Synonyms: Niagara, Niagara Falls. · · Noun Definition 1 (noun) a river flowing from Lake Erie into Lake Ontario; forms boundary between Ontario and New York. Synonyms: Niagara, Niagara River. · · Noun Definition 2 Characters · · a latin small letter a U+0061 g latin small letter g U+0067 i latin small letter i U+0069 n latin small letter n U+006E r latin small letter r U+0072