Definition of "caustic" []

• Capable of burning, corroding, dissolving, or eating away by chemical action. (adjective)
• Corrosive and bitingly trenchant; cutting. See Synonyms at sarcastic. (adjective)
• Causing a burning or stinging sensation, as from intense emotion: "Most of all, there is caustic shame for my own stupidity” ( Scott Turow). (adjective)
• A caustic material or substance. (noun)
• A hydroxide of a light metal. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "While on this subject of caustic potash, it cannot be too often repeated that _caustic potash_ is a totally different article to _caustic soda_, though just like it in appearance, and therefore often sold as such."
• "The common caustic, called _lunar caustic_, is a compound formed by the union of nitric acid and silver; and it is supposed to owe its caustic qualities to the oxygen contained in the nitric acid."
• "The term caustic to a tender ear (and I conceive none feel more interested in this inquiry than the anxious guardians of a nursery) may sound harsh and unpleasing, but every solicitude that may arise on this account will no longer exist when it is understood that the pustule, in a state fit to be acted upon, is then quite superficial, and that it does not occupy the space of a silver penny. 25"