Definition of caustic in English:

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Pronunciation: /ˈkɔːstɪk/
Pronunciation: /ˈkɒstɪk/


1Able to burn or corrode organic tissue by chemical action: a caustic cleaner
More example sentences
  • The list includes sodium hydroxide and potassium hydroxide, caustic chemicals that will rip the skin off your fingers and the lining from the throat.
  • Sodium hydroxide is a caustic type of chemical that actually softens hair fibers.
  • Some of the chemicals - including caustic hydrogen fluoride and deadly arsine gas - are toxic, and the fossil fuel consumed contributes to global warming, says Williams.
corrosive, corroding, mordant, acid, alkaline, burning, stinging, acrid, harsh, destructive
2Sarcastic in a scathing and bitter way: the players were making caustic comments about the refereeing
More example sentences
  • Her caustic, waspish comments on the other housemates were biting and bitchy, but always spot on.
  • She's really quite funny, in a bitter, caustic kind of way.
  • The pattern of caustic complaints and sarcastic responses slowly gave way to a new pattern of care toward one another.
sarcastic, cutting, biting, mordant, stinging, sharp, bitter, scathing, derisive, sardonic, ironic, scornful, trenchant, acerbic, vitriolic, tart, acid, pungent, acrimonious, astringent, rapier-like, razor-edged, critical, polemic, virulent, venomous, waspish
British informal sarky
rare mordacious, acidulous
3 Physics Formed by the intersection of reflected or refracted parallel rays from a curved surface.
Example sentences
  • In On burning mirrors Diocles also studies the problem of finding a mirror such that the envelope of reflected rays is a given caustic curve or of finding a mirror such that the focus traces a given curve as the Sun moves across the sky.
  • Sturm's theoretical work in mathematical physics involved the study of caustic curves, and poles and polars of conic sections.
  • For example they worked together on caustic curves during 1692-93 although they did not publish the work jointly.


1A caustic substance.
Example sentences
  • Spent grain, yeast, ethanol, and acids and caustics used for cleaning are all sent out to be used for feed for cattle or reprocessed and reused industrially.
  • Production is potentially dangerous, as you need to heat volatile methanol with caustics.
  • The scenes below show caustics, which are very difficult to render.
2 Physics A caustic surface or curve.
Example sentences
  • Nevertheless, this elucidation of the generic discontinuous change has shed light upon many optical phenomena where caustics and diffraction occur.
  • The caustic of a circle with radiant point on the circumference is a cardioid, while if the rays are parallel then the caustic is a nephroid.
  • The caustic of the equiangular spiral, where the pole is taken as the radiant, is an equal equiangular spiral.



Pronunciation: /ˈkɔːstɪk(ə)li/
Example sentences
  • Unfortunately, however, they have now become a version of the mid-1960s caucus which a reformist Whitlam so caustically described at the time: small and witless men.
  • It is strangely unclassifiable television - a caustically comic, surreptitiously sudsy thriller that has alienated a whole tranche of strait-laced Americans and so delighted many more.
  • Maybe it is in his corner, but as one Indonesian newspaper commented caustically, ‘No doubt the police feel safe, because they have guns.’


Pronunciation: /kɔːsˈtɪsɪti/
Pronunciation: /kɒsˈtɪsɪti/
Example sentences
  • ‘A Dirty Shame’ finds Waters basking in the wildness of such fun, but the film is also a retreat from his more sophisticated causticity.
  • ‘The saliva of termites has great causticity, although it is not strong enough to destroy concrete buildings,’ said Cheng Ruihua, a termite exterminator in Yangpu District for over 30 years.
  • One is tempted, with undue causticity perhaps, to ask - like Emperor Joseph II at the premiere of Mozart's ‘Abduction from the Seraglio ‘- whether her prose does not, in fact, have ‘too many notes.’


Late Middle English: via Latin from Greek kaustikos, from kaustos 'combustible', from kaiein 'to burn'.

  • English caustic came via Latin from Greek kaustikos, from kaiein ‘to burn’, also the base of cauterize (Late Middle English).

For editors and proofreaders

Line breaks: caus|tic

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