1. A great fall of water over a precipice; as that of Niagara, of the Rhine, Danube and Nile. It is a cascade upon a great scale.
The tremendous cataracts of America thundering in their solitudes.
2. In medicine and surgery, an opacity of the cystaline lens, or its capsule; a disorder in the eye, by which the pupil, which is usually black and transparent, becomes opake, blue, gray, brown, etc., by which vision is impaired or destroyed.