cataract

noun

cat·​a·​ract ˈka-tə-ˌrakt How to pronounce cataract (audio)
1
[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
2
a
obsolete : waterspout
b
: waterfall
especially : a large one over a precipice
c
: steep rapids in a river
the cataracts of the Nile
d
: downpour, flood
cataracts of rain
cataracts of information
cataractous adjective

Did you know?

The ocular meaning of cataract that English users are most familiar with is also the oldest. It dates to the 14th century and comes from the Latin word cataracta, meaning “portcullis,” probably because a cataract in one’s eye obstructs vision much like a 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,” describing the action of 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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The curtains were shut across all of their windows - Jo was recovering from cataract surgery. Morgan Lieberman, NPR, 26 June 2025 Chris Klomp, director of the Center for Medicare at CMS, recommended prior authorization be eliminated for vaginal deliveries, colonoscopies, and cataract surgeries, among other procedures. Lauren Sausser, NBC news, 24 June 2025 Medicare Director Chris Klomp gave the example of colonoscopies or cataract surgeries as procedures that could be moved out of the prior authorization process. Joseph Choi, The Hill, 23 June 2025 Care that may no longer be subject to preapproval includes colonoscopies, cataract surgeries and two-day hospital stays after vaginal births, said Chris Klomp, who leads CMS’ Center for Medicare. Tami Luhby, CNN Money, 23 June 2025 See All Example Sentences for cataract

Word History

Etymology

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

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Cite this Entry

“Cataract.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cataract. Accessed 30 Jun. 2025.

Kids Definition

cataract

noun
cat·​a·​ract ˈkat-ə-ˌrakt How to pronounce cataract (audio)
1
: a clouding of the lens of the eye or of the transparent cover around it that blocks the passage of light
2
a
: a large waterfall
b
: a sudden rush like a waterfall : flood

Medical Definition

cataract

noun
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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