caustic
Americanadjective
noun
-
a caustic substance.
-
Optics.
adjective
-
capable of burning or corroding by chemical action
caustic soda
-
sarcastic; cutting
a caustic reply
-
of, relating to, or denoting light that is reflected or refracted by a curved surface
noun
-
Also called: caustic surface. a surface that envelops the light rays reflected or refracted by a curved surface
-
Also called: caustic curve. a curve formed by the intersection of a caustic surface with a plane
-
chem a caustic substance, esp an alkali
Other Word Forms
Derived Forms
Etymology
Origin of caustic
1350–1400; Middle English < Latin causticus < Greek kaustikós burning, caustic, equivalent to kaust ( ós ) burnt (verbal adjective of kaíein to burn) + -ikos -ic
Explanation
Use the adjective caustic to describe any chemical that is able to burn living tissue or other substances, or, figuratively, a statement that has a similarly burning effect. Caustic in this sense means harshly critical. In the chemical sense, a near synonym is corrosive. In the figurative sense, near synonyms are biting, scathing, and sarcastic. The source of the word caustic is Latin causticus, from Greek kaustikos, from kaiein "to burn."
Vocabulary lists containing caustic
The SAT: Words to Capture Tone, List 1
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
The New SAT: Words to Capture Tone
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
100 Words to Make You Sound Smart
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The pair creates a diamond-shaped feature known as a caustic curve, where stars can appear dramatically brighter.
From Science Daily • Jun. 5, 2026
A chemical, thought to be caustic soda, is understood to have entered the water at the Knockando burn, which flows into the River Spey, in the last few days.
From BBC • May 3, 2026
She’s forward and caustic, with a sharp wit and a hefty Jersey accent that doesn’t exactly scream “therapist’s office” — unless your therapist is Dr. Melfi from “The Sopranos,” in which case, lucky you.
From Salon • Apr. 29, 2026
The federal investigators encountered puddles of crude oil on the facility grounds, as well as caustic fumes emanating from the facility, resulting in violations for air quality and other environmental infractions.
From Los Angeles Times • Feb. 14, 2026
If Kilvin’s demonstration was any indication, I guessed the whole shop could be a sea of flame and caustic fog in less than a minute.
From "The Name of the Wind" by Patrick Rothfuss
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
