1. A large or high waterfall.
2. A great downpour; a deluge.
3. 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.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.