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
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.