Pronunciation: (nī-ag'ru, -ag'ur-u),[key] —n. 1. a river on the boundary between W New York and Ontario, Canada, flowing from Lake Erie into Lake Ontario. 34 mi. (55 km) long.
2. See Niagara Falls. 3. Fort, a fort in W New York, at the mouth of the Niagara River.
4. (l.c.) anything taken as resembling Niagara Falls in force and relentlessness; avalanche: a niagara of criticism. 5. Hort. a. a variety of white grape, grown for table use.
b. the vine bearing this fruit.