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

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

Did you know?

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, causalgia (a burning pain caused by nerve damage), and encaustic (a kind of paint that 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.
Recent Examples on the Web: Adjective On their own, these five gents are now a little older and mellower, still funny, still caustic and still extremely smart individuals. David Fear, Rolling Stone, 14 May 2022 Neither the Biden administration nor Ukrainian President Volodymyr Zelensky has officially confirmed the accounts of a chemical attack, which was alleged to have involved an unknown caustic substance dropped from a Russian drone. Washington Post, 12 Apr. 2022 The caustic causes Earendel to stand out, with Its brightness is magnified a thousandfold or more. Julia Musto, Fox News, 31 Mar. 2022 But sodium hydroxide is only highly caustic or corrosive in high doses, Dr. Christopher Holstege, a medical toxicologist at the University of Virginia, told USA TODAY. Sudiksha Kochi, USA TODAY, 21 Mar. 2022 Their rhythmic and caustic dialogue immediately confirms the sharpness of Fillinger’s pen. Lovia Gyarkye, The Hollywood Reporter, 28 Apr. 2022 Roberts makes Martha Mitchell compelling, moving from caustic and charming to terrified, as in a harrowing episode that shows what the late Mitchell said was an attempt to shut her up, as she was held against her will at a California hotel. oregonlive, 20 Apr. 2022 But the humor is delivered in a similar manner, not by way of plot as much as through the asides and random comments batted back and forth among the show’s principal three and their casual and caustic observations on modern life and expectations. John Anderson, WSJ, 6 Jan. 2022 The area is surrounded by other caustic industry, including an asphalt plant. Joshua Bowling, The Arizona Republic, 12 Apr. 2022 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 See More

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.

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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Statistics for caustic

Last Updated

22 May 2022

Cite this Entry

“Caustic.” Dictionary, Merriam-Webster, Accessed 22 May. 2022.

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More Definitions for caustic


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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