cataract

Short definition from Wiktionary

Noun

1. 1
   A (large) waterfall, specifically one flowing over the edge of a cliff.
2. 2
   A flood of water; specifically, steep rapids in a river.
3. 3
   An overwhelming downpour or rush; a flood.
4. 4
   A type of governor used in single-acting steam engines, where a flow of water through an opening regulates the stroke.
5. 5
   Synonym of waterspout (“a whirlwind that forms over water”).
6. 6
   Synonym of portcullis (“a gate in the form of a grating which is lowered into place at the gateway of a castle, a fort, etc.”); also, a window grating.
7. 7
   A clouding of the lens in the eye leading to a decrease in vision.
8. 8
   A clouding of the lens in the eye leading to a decrease in vision: Something which obscures.
9. 9
   A tool used for breaking flax; a brake.

Verb

1. 1
   Of a river, etc.: to fall in the form of a waterfall.
2. 2
   To cause (something) to pour or rush like a waterfall.