cataclysm
noun
cat·a·clysm ˈka-tə-ˌkli-zəm 
1
: flood, deluge
2
: catastrophe sense 3a
3
: a momentous and violent event marked by overwhelming upheaval and demolition
broadly : an event that brings great changes
an international economic cataclysm
cataclysmal
ˌka-tə-ˈkliz-məl
adjective or cataclysmic
ˌka-tə-ˈkliz-mik
cataclysmically
ˌka-tə-ˈkliz-mi-k(ə-)lē
adverb 
Synonyms
- alluvion
- bath
- cataract
- deluge
- flood
- flood tide
- inundation
- Niagara
- overflow
- spate
- torrent
See all Synonyms & Antonyms 
Example Sentences
floods, earthquakes, and other cataclysms The country barely survived the cataclysm of war. The revolution could result in worldwide cataclysm.
Recent Examples on the Web Fogerty wrote all three of them right around the original Earth Day, and each one works weather metaphors almost too on-the-nose for the climate-change cataclysm at hand. 
David Cantwell, The New Yorker, 17 Aug. 2022 Federal Reserve chair Jerome Powell, meanwhile, doesn't foresee market cataclysm once the bear market officially begins. Nicole Goodkind, CNN, 20 May 2022 In any event, between 1975 and 1979 possibly more than two million people were murdered in this cataclysm. Deborah Eisenberg, The New York Review of Books, 19 Aug. 2021 This cataclysm spewed huge amounts of gases that geologists suspect altered the global climate and led to the extinction of nearly 80 percent of life on the planet—though the dinosaurs somehow survived and later thrived. Sasha Warren, Scientific American, 1 July 2022 Wilder’s play, an absurdist survey of humankind’s remarkable endurance through all manner of cataclysm across the ages, doesn’t need the layers of attitudinal commentary Blain-Cruz adds. Washington Post, 29 Apr. 2022 Known as the Black Death, the cataclysm of 1346-1352 is still the most deadly pandemic in human history. Kiona N. Smith, Ars Technica, 21 June 2022 Politics in Berlin has undergone a political cataclysm that no one saw coming. Noah Barkin, The Atlantic, 1 Mar. 2022 An Everest-size comet is hurtling toward Earth, and in exactly six months and 14 days, the planet will be shattered to pieces, leaving every living creature to perish in a cataclysm of fire and flood. Maya Salam, New York Times, 23 Jan. 2022 See More
David Cantwell, The New Yorker, 17 Aug. 2022 Federal Reserve chair Jerome Powell, meanwhile, doesn't foresee market cataclysm once the bear market officially begins. Nicole Goodkind, CNN, 20 May 2022 In any event, between 1975 and 1979 possibly more than two million people were murdered in this cataclysm. Deborah Eisenberg, The New York Review of Books, 19 Aug. 2021 This cataclysm spewed huge amounts of gases that geologists suspect altered the global climate and led to the extinction of nearly 80 percent of life on the planet—though the dinosaurs somehow survived and later thrived. Sasha Warren, Scientific American, 1 July 2022 Wilder’s play, an absurdist survey of humankind’s remarkable endurance through all manner of cataclysm across the ages, doesn’t need the layers of attitudinal commentary Blain-Cruz adds. Washington Post, 29 Apr. 2022 Known as the Black Death, the cataclysm of 1346-1352 is still the most deadly pandemic in human history. Kiona N. Smith, Ars Technica, 21 June 2022 Politics in Berlin has undergone a political cataclysm that no one saw coming. Noah Barkin, The Atlantic, 1 Mar. 2022 An Everest-size comet is hurtling toward Earth, and in exactly six months and 14 days, the planet will be shattered to pieces, leaving every living creature to perish in a cataclysm of fire and flood. Maya Salam, New York Times, 23 Jan. 2022 See More Word History
Etymology
French cataclysme, from Latin cataclysmos, from Greek kataklysmos, from kataklyzein to inundate, from kata- + klyzein to wash — more at clyster
First Known Use
1599, in the meaning defined at sense 1
cataclysmal
adjective
variants or cataclysmic
1
as in disastrous
bringing about ruin or misfortune a cataclysmal decision to plunge the nation into war Synonyms & Similar Words
Relevance
- disastrous
- catastrophic
- fatal
- destructive
- ruinous
- damning
- unfortunate
- adverse
- fateful
- calamitous
- damaging
- apocalyptic
- pernicious
- apocalyptical
- harmful
- detrimental
- evil
- hurtful
- hapless
- deleterious
- ill-fated
- prejudicial
- ill-starred
- luckless
- baneful
- injurious
- noxious
- baleful
- ill
Antonyms & Near Antonyms
- happy
- lucky
- fortuitous
- fortunate
- optimistic
- fair
- golden
- promising
- propitious
- bright
- fluky
- providential
- encouraging
- hopeful
- rosy
- upbeat
- auspicious
- flukey
- heartening
- rose-colored
2
as in devastative
causing or tending to cause destruction a cataclysmal landslide that virtually wiped out the village Synonyms & Similar Words
- devastative
- devastating
- disastrous
- destructive
- annihilatory
- poisonous
- fell
- ruinous
- fatal
- lethal
- deadly
- calamitous
- murderous
- antibiotic
- killer
- virulent
- harmful
- pernicious
- detrimental
- biocidal
- deleterious
- deathly
- vital
- mortal
- baleful
- pestilent
Antonyms & Near Antonyms
- protective
- nondestructive
- creative
- productive
- constructive
- useful
- helpful
- harmless
- healthy
- innocent
- formative
- innocuous
- healthful
- preservative
- wholesome
- inoffensive
- nonlethal
- salubrious
- ameliorative
- nonfatal
3
as in turbulent
marked by sudden or violent disturbance the French Revolution was one of the great cataclysmal events in modern history Synonyms & Similar Words
- turbulent
- sporadic
- tumultuous
- stormy
- convulsive
- spasmodic
- noisy
- boisterous
- tempestuous
- riotous
- furious
- fitful
- clamorous
Antonyms & Near Antonyms
- peaceful
- undisturbed
- unperturbed
- tranquil
- calm
- serene
- placid
- untroubled
- unshaken
- reflectorises
- reflectorising
- reflectorize
- reflectorized
- reflectorizes
- reflectorizing
- reflectors
- reflects
- reflects (on or upon)
- reflects on or upon
- reflesher
- reflet
- reflets
- reflew
- reflex
- reflex arc
- reflex camera
- reflex sympathetic dystrophy
- reflexed
- reflexed bow
- reflexer
- reflexes
- reflexest
- reflexibility
- reflexible