caustic

1 of 3

adjective

caus·​tic ˈkȯ-stik 

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)

caustically

ˈkȯ-sti-k(ə-)lē 

adverb

causticity

kȯ-ˈsti-sə-tē 

noun

caustic

2 of 3

noun (1)

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

causticity

3 of 3

noun (2)

caus·​tic·​i·​ty kȯ-ˈsti-sə-tē 

plural -es

1

: the quality or state of being caustic : corrosiveness

the causticity of potash

2

: dry tart sharpness especially of biting wit

the causticity of his retort

Did you know?

If you have a burning desire to know the origins of caustic, you're already well on your way to figuring it out. Caustic was formed in Middle English as an adjective describing chemical substances, such as lime and lye, that are capable of destroying or eating away at something. The word is based on the Latin adjective causticus, which itself comes ultimately from the Greek verb kaiein, meaning "to burn." In time, caustic was baked into the English language as an adjective describing people or things (such as wit or remarks) that are bitingly sarcastic. 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).

Synonyms of caustic

Adjective

• sarcastic
• satiric
• acidic
• acid
• barbed
• corrosive

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

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

The press was its usual caustic self this weekend, filled with talk about delusional investors who will have a hard lesson to learn. —Jim Cramer, CNBC, 14 June 2026

Also, caustic chemicals such as muriatic acid should be in plastic since a bottle of such substances could have very bad results. —Chicago Tribune, 6 June 2026

This process uses caustic liquids and high temperatures to extract and refine alumina from bauxite ore. —Atharva Gosavi, Interesting Engineering, 6 June 2026

White liquor is caustic, authorities said, and is used in the production of paper products. —Jeanine Santucci, USA Today, 31 May 2026

Word History

Etymology

Adjective and Noun (1)

Latin causticus, from Greek kaustikos, from kaiein to burn

Noun (2)

French causticité, from Latin causticus + French -ité -ity

First Known Use

Adjective

14th century, in the meaning defined at sense 1

Noun (1)

15th century, in the meaning defined at sense 1

Phrases Containing caustic

• caustic potash
• caustic soda
• lunar caustic

Rhymes for caustic

• gnostic
• acrostic
• agnostic
• encaustic
• prognostic
• diagnostic

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Kids Definition

caustic

1 of 2 adjective

caus·​tic ˈkȯ-stik 

1

: capable of eating away by chemical action : corrosive

2

: likely to offend or hurt someone's feelings

a caustic remark

caustically

-sti-k(ə-)lē 

adverb

caustic

2 of 2 noun

: a caustic substance (as caustic soda)

Medical Definition

caustic

1 of 2 adjective

caus·​tic ˈkȯ-stik 

: capable of destroying or eating away organic tissue and especially animal tissue by chemical action

silver nitrate and sulfuric acid are caustic agents

caustically

-sti-k(ə-)lē 

adverb

causticity

kȯ-ˈstis-ət-ē 

noun

plural causticities

caustic

2 of 2 noun

: 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)