Cat"a*ract (?), n. [L.
cataracta, catarracles, a waterfall, Gr. &?;, &?;,
fr. &?; to break down; in the passive, to fall or rush down (of
tumors) to burst; kata` down + &?; to break.]
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.