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?

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.

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

With this new technology, the team hopes to one day determine if intraocular lenses — surgically implanted permanent lenses that replace the natural eye lens after cataract surgery — may contribute to nanoplastics in the body. —Discover Magazine, 14 Apr. 2025

This habit can increase the risk of AMD and cataracts and damage the optic nerve. —Cristina Mutchler, Verywell Health, 11 Oct. 2024

The summary noted that Trump previously had cataract surgery on both eyes, but did not include a date or dates. —Darlene Superville, Chicago Tribune, 13 Apr. 2025

The report also revealed that the president underwent a colonoscopy last July, when he was diagnosed with diverticulitis and a benign polyp, and had cataract surgery at some undetailed point in the past. —Matthew Medsger, Boston Herald, 13 Apr. 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

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