cataract

noun cat·a·ract \ ˈka-tə-ˌrakt \

Updated on: 26 Apr 2018

Definition of cataract

[Middle English, from Medieval French or Medieval Latin; Medieval 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

play \ˌka-tə-ˈrak-təs\ adjective

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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 of cataract from the Web

In addition, cataracts, which occur in nearly 50% of people ages 75 to 80, should be addressed early to decrease your risk of falls.

— dr. melina jampolis, CNN, "Aging gracefully: Preventing falls," 19 Apr. 2018
These cells accumulate in the body with age and cause inflammation, arthritic joints and cataracts.

— catherine ho, San Francisco Chronicle, "Bezos-backed anti-aging startup seeks to raise $85 million in potential IPO," 6 Apr. 2018
Mike has cataracts — causing him to be totally blind in his right eye and limiting his vision in his left eye to about 50%.

— brandon patterson, Detroit Free Press, "Michigan man takes pet cow on 2,200-mile road trip to save its eyesight," 28 Mar. 2018
Medical concerns facing the midwives will include everything from breech birth to cancer, Huntington's chorea, and cataracts.

— caroline hallemann, Town & Country, "Call the Midwife," 12 Mar. 2018
The two cataracts on the footprint of the World Trade Center demand attention by dint of their enormous size alone: Millions of feet of commercial real estate were ceded to the National September 11 Memorial and Museum.

— alexander nazaryan, Newsweek, "New York City Would Really Rather Not Talk About Its Slavery-Loving Past," 15 Apr. 2015
Ozone blocks ultraviolet radiation from the sun, which can cause health problems ranging from cataracts and other eye problems to premature skin aging and potentially fatal skin cancers.

— david freeman /, NBC News, "The good news about the ozone hole is even better than you think," 9 Jan. 2018
In America, congenital cataracts—a clouding of the eye lens at birth that can lead to blindness—are vanishingly (and thankfully) uncommon.

— ben panko, Smithsonian, "Can Eagle-Eyed Artificial Intelligence Help Prevent Children From Going Blind?," 1 Feb. 2017
The treatment has potential side effects, including macular thinning, ocular pressure, cataracts, retinal tears, and eye inflammation.

— linda loyd, Philly.com, "FDA approves Spark's gene therapy for rare blindness pioneered at CHOP," 19 Dec. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cataract.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Did You Know?

The meaning of "cataract" we're most familiar with is also the oldest. It dates to the 14th century and comes from the Latin word cataracta, meaning "portcullis," probably because the ocular cataract obstructs vision in a way reminiscent of the way the portcullis's heavy iron grating obstructs passage into a fortress or castle. Latin cataracta has another meaning, however-"waterfall"-and that meaning gave us 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.