caus·​tic | \ ˈkȯ-stik How to pronounce caustic (audio) \

Definition of caustic

 (Entry 1 of 2)

1 : capable of destroying or eating away by chemical action : corrosive The chemical was so caustic that it ate through the pipe.
2 : marked by incisive sarcasm a caustic film review caustic humor
3 : relating to or being the surface or curve of a caustic (see caustic entry 2 sense 2)



Definition of caustic (Entry 2 of 2)

1 : a caustic agent: such as
a : a substance that burns or destroys organic tissue by chemical action
b : a strong corrosive alkali (such as sodium hydroxide)
2 : the envelope of rays emanating from a point and reflected or refracted by a curved surface

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Other Words from caustic


caustically \ ˈkȯ-​sti-​k(ə-​)lē How to pronounce caustic (audio) \ adverb
causticity \ kȯ-​ˈsti-​sə-​tē How to pronounce caustic (audio) \ noun

Choose the Right Synonym for caustic


caustic, mordant, acrid, scathing mean stingingly incisive. caustic suggests a biting wit. caustic comments mordant suggests a wit that is used with deadly effectiveness. mordant reviews of the play acrid implies bitterness and often malevolence. acrid invective scathing implies indignant attacks delivered with fierce severity. a scathing satire

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If you have a burning desire to know the origins of "caustic," you're already well on the way to figuring it out. "Caustic" was borrowed into English in the 14th century from the Latin causticus, which itself derives from the Greek kaustikos. "Kaustikos," in turn, comes from the Greek verb kaiein, meaning "to burn." Other "kaiein" descendants in English include "cautery" and "cauterize," "hypocaust" (an ancient Roman heating system), "causalgia" (a burning pain caused by nerve damage), and "encaustic" (a kind of paint which is heated after it's applied).

Examples of caustic in a Sentence

Adjective His [Roosevelt's] caustic cousin, Alice Roosevelt Longworth, called him a sissy and a mama's boy. — Garry Wills, Atlantic, April 1994 It was Schuyler's gift for satire and his caustic wit that distinguished his writings and led to his nickname, the Black Mencken. — Henry Louis Gates, Jr., New York Times Book Review, 20 Sept. 1992 Albert quailed before those caustic pronouncements, he shuddered and blanched and felt his stomach drop like a croquette into a vat of hot grease. — T. Coraghessan Boyle, Harper's, October 1987 The chemical was so caustic that it ate through the pipes. She wrote a caustic report about the decisions that led to the crisis.
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Recent Examples on the Web: Adjective The caustic outing of Gaustad's sexuality amplified her anxiety and depression. Billboard, 7 Oct. 2021 Set in seventeenth-century Brazil, the novel revolves around Almeyda, a Black slave girl, who lives on a plantation with her watchful mother and her caustic grandmother. The New Yorker, 27 Sep. 2021 Every day, crowded cells holding people at an immigration detention facility in Florida have been doused with caustic disinfectants that have caused breathing problems and bleeding, according to reports from the detainees. Matthew Phelan, Scientific American, 17 Sep. 2021 In March, Neera Tanden, his pick to head the budget office, pulled out of contention after an uproar over her caustic public statements., 9 Sep. 2021 The sound is industrial, like the caustic hum of an ancient generator. Sam Gillette,, 8 Sep. 2021 Jazz Age America, the world into which his caustic, droll and raunchy poem was released, was, no question, violent and corrupt and cynical. New York Times, 6 Sep. 2021 Republicans saw suburban voters flee under Trump, turned off by his caustic rhetoric and uncaring attacks on scores of people. Dan Merica, CNN, 5 Sep. 2021 Or the self that's harshly critical of self and tends to see others with irritation, annoyance and caustic judgment? Joel M. Rothaizer, Forbes, 1 Sep. 2021 Recent Examples on the Web: Noun What McHugh favored was the fantastic, the caustic, the nakedly human, art with an irreverent or whimsical sense of humor, and art with little remove from raw physicality. Leah Ollman,, 3 July 2018 The Sympathizer is the caustic, hyper-verbal tale of a double agent embedded in California after the end of the war, sending information back to Vietnam about the activities of the men who are both his friends and enemies. Josephine Livingstone, New Republic, 25 July 2017 Mr. Trump’s other mentor was the caustic and conniving McCarthy-era lawyer Roy Cohn, who counseled Mr. Trump never to give in or concede error. Glenn Thrush And Maggie Haberman, New York Times, 21 Mar. 2017

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

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First Known Use of caustic


14th century, in the meaning defined at sense 1


15th century, in the meaning defined at sense 1

History and Etymology for caustic

Adjective and Noun

Latin causticus, from Greek kaustikos, from kaiein to burn

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Time Traveler for caustic

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The first known use of caustic was in the 14th century

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Dictionary Entries Near caustic



caustic alcohol

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Last Updated

13 Oct 2021

Cite this Entry

“Caustic.” Dictionary, Merriam-Webster, Accessed 20 Oct. 2021.

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More Definitions for caustic



English Language Learners Definition of caustic

: able to destroy or burn something by chemical action
: very harsh and critical


caus·​tic | \ ˈkȯ-stik How to pronounce caustic (audio) \

Kids Definition of caustic

1 : capable of eating away by chemical action : corrosive
2 : very harsh and critical caustic remarks


caus·​tic | \ ˈkȯ-stik How to pronounce caustic (audio) \

Medical Definition of caustic

 (Entry 1 of 2)

: capable of destroying or eating away organic tissue and especially animal tissue by chemical action silver nitrate and sulfuric acid are caustic agents

Other Words from caustic

caustically \ -​sti-​k(ə-​)lē How to pronounce caustic (audio) \ adverb
causticity \ kȯ-​ˈstis-​ət-​ē How to pronounce caustic (audio) \ noun, plural causticities



Medical Definition of caustic (Entry 2 of 2)

: a caustic agent: as
a : a substance that burns or destroys organic tissue by chemical action : escharotic
b : a strong corrosive alkali (as sodium hydroxide)

More from Merriam-Webster on caustic

Nglish: Translation of caustic for Spanish Speakers


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