| 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. | Niagara Falls. |
| 3. | Fort, a fort in W New York, at the mouth of the Niagara River. |
| 4. | (lowercase ) anything taken as resembling Niagara Falls in force and relentlessness; avalanche: a niagara of criticism. |
| 5. | Horticulture.
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| Niagara River A river flowing about 55 km (34 mi) from Lake Erie to Lake Ontario. It forms part of the boundary between western New York and Ontario, Canada. |