cat·​a·​ract ˈka-tə-ˌrakt How to pronounce cataract (audio)
[Middle English, from Middle French or Medieval Latin; Middle French catharacte, from Medieval Latin cataracta, from Latin, portcullis] : a clouding of the lens of the eye or of its surrounding transparent membrane that obstructs the passage of light
obsolete : waterspout
: waterfall
especially : a large one over a precipice
: steep rapids in a river
the cataracts of the Nile
: downpour, flood
cataracts of rain
cataracts of information
cataractous adjective

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Cataract dates to the 14th century and comes from the Latin word cataracta, meaning "portcullis." The Latin pertains to the ocular cataract, probably because it obstructs one's vision much like the portcullis's heavy iron grating obstructs passage into a fortress or castle. Cataracta has another meaning, however—"waterfall"—and that meaning gave English the water-related meanings that came in later centuries. The connection between the two Latin meanings can be seen in katarassein, the Greek source of cataracta. It means "to dash down," an action we see in both the slamming portcullis and the cascading waterfall.

Examples of cataract in a Sentence

the roaring cataract is one of the park's most majestic sights in spring the melting snows usually produce a cataract that inundates the valley
Recent Examples on the Web Similar changes were not detected in individuals with reversed cataracts that emerged later in childhood. Cordula Hölig, Scientific American, 12 May 2023 As Claude Monet got older, cataracts began to cloud his vision. Sarah Kuta, Smithsonian Magazine, 10 Oct. 2023 Steroids can cause cataracts, osteoporosis and other complications if used in excess or for too long. Moises Velasquez-Manoff, New York Times, 4 Oct. 2023 The formation of cataracts, which cause cloudiness in the eye’s natural lens, is very common as people age: Half of people 75 and older have them. Bernard J. Wolfson, San Diego Union-Tribune, 3 Oct. 2023 Guided by the center’s doctors, Sophie got to test her skills in cataract surgery. Simon Perry, Peoplemag, 12 Oct. 2023 Sara had traveled to Washington state in January 1933 from her Alaska hometown to accompany her mother for cataract surgery. Nicole Dungca and Claire Healy, Anchorage Daily News, 10 Sep. 2023 In ancient Mexico, powdered obsidian was mixed with quartz and sprinkled in someone’s eyes to treat cataracts. Jim Robbins, New York Times, 20 Mar. 2023 Vargas, 69, who had no major health problems except gout and cataracts, had died on his tractor. Elizabeth Weise, USA TODAY, 13 Aug. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'cataract.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Latin cataracta waterfall, portcullis, from Greek kataraktēs, from katarassein to dash down, from kata- + arassein to strike, dash

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of cataract was in the 14th century


Dictionary Entries Near cataract

Cite this Entry

“Cataract.” Dictionary, Merriam-Webster, Accessed 4 Dec. 2023.

Kids Definition


cat·​a·​ract ˈkat-ə-ˌrakt How to pronounce cataract (audio)
: a clouding of the lens of the eye or of the transparent cover around it that blocks the passage of light
: a large waterfall
: a sudden rush like a waterfall : flood

Medical Definition


cat·​a·​ract ˈkat-ə-ˌrakt How to pronounce cataract (audio)
: a clouding of the lens of the eye or its surrounding transparent membrane that obstructs the passage of light

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