cat·a·ract   (kāt'ə-rākt')    n.   A large or high waterfall. A great downpour; a deluge. Pathology Opacity of the lens or capsule of the eye, causing impairment of vision or blindness. [Middle English cataracte, from Old French, from Latin cataracta, from Greek katarraktēs, kataraktēs, downrush, waterfall, portcullis, probably from katarassein, to dash down (kat-, kata-, cata- + arassein, to strike). Sense 3, from a comparison to a portcullis or other falling impediment or covering.] cat'a·rac'tous (-rāk'təs) adj.

Cataract

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.

cataract [(kat-uh-rakt)]

A loss in the transparency of the lens of the eye, which reduces a person's ability to see. The condition can be treated by surgically removing the lens and replacing it with an artificial one, or with corrective eyeglasses or contact lenses.

cataract 

Main Entry: cat·a·ract
Pronunciation: 'kat-&-"rakt
Function: noun
: a clouding of the lens of the eye or its surrounding transparentmembrane that obstructs the passage of light

cataract cat·a·ract (kāt'ə-rākt')
n.
Opacity of the lens or capsule of the eye, causing impairment of vision or blindness.

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cat'a·rac'tous (-rāk'təs) adj.

cataract   (kāt'ə-rākt')  Pronunciation Key  An opacity of the lens of the eye or the membrane that covers it, causing impairment of vision or blindness. A waterfall in which a large volume of water flows over a steep precipice.