cat·a·ract /ˈkætəˌrækt/ 名詞
1. A great fall of water over a precipice; a large waterfall.
2. Surg. An opacity of the crystalline lens, or of its capsule, which prevents the passage of the rays of light and impairs or destroys the sight.
3. Mach. A kind of hydraulic brake for regulating the action of pumping engines and other machines; -- sometimes called dashpot.
n 1: clouding of the natural lens of the eye
2: a large waterfall; violent rush of water over a precipice