cataract

noun

cat·​a·​ract ˈka-tə-ˌrakt 

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

ˌka-tə-ˈrak-təs 

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.

Synonyms

• cascade
• fall(s)
• 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

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

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

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Kids Definition

cataract

noun

cat·​a·​ract ˈkat-ə-ˌrakt 

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 

: a clouding of the lens of the eye or its surrounding transparent membrane that obstructs the passage of light