acid

noun

Definition of acid

 (Entry 1 of 2)

1 : a sour substance specifically : any of various typically water-soluble and sour compounds that in solution are capable of reacting with a base (see base entry 1 sense 7a) to form a salt, redden litmus, and have a pH less than 7, that are hydrogen-containing molecules or ions able to give up a proton to a base, or that are substances able to accept an unshared pair of electrons from a base
2 : something incisive, biting, or sarcastic a social satire dripping with acid
3 : lsd

acid

adjective
ac·​id | \ ˈa-səd \

Definition of acid (Entry 2 of 2)

1a : sour, sharp, or biting to the taste an acid flavor
b : sharp, biting, or sour in manner, disposition, or nature an acid individual an acid personality
c : sharply clear, discerning, or pointed an acid wit acid criticism
d : piercingly intense and often jarring acid yellow
2a : of, relating to, or being an acid also : having the reactions or characteristics of an acid acid soil an acid solution
b of salts and esters : derived by partial exchange of replaceable hydrogen acid sodium carbonate NaHCO3
c : containing or involving the use of an acid (as in manufacture) an acid bath
d : marked by or resulting from an abnormally high concentration of acid acid indigestion
3 : relating to or made by a process in which the furnace is lined with acidic material and an acidic slag is used acid steel
4 : rich in silica acid rocks

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Other Words from acid

Noun

acidy \ ˈa-​sə-​dē \ adjective

Adjective

acidly adverb
acidness noun

Synonyms for acid

Synonyms: Adjective

acidic, acidulous, sour, sourish, tart, tartish, vinegary

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Examples of acid in a Sentence

Noun

the acids in your stomach the kinds of acid found in your stomach

Adjective

He washes his windows with an acid solution of vinegar and water. with her acid personality, my aunt could be relied upon to bring some much-needed balance to the holiday gush
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Recent Examples on the Web: Noun

Your larger-than-usual uterus can also crowd your stomach and thrust digestive acids upward, creating heartburn in the process. Korin Miller, SELF, "7 Ways to Make Sleep More Comfortable When You’re Pregnant," 31 Jan. 2019 The acid attacks the termites’ digestive systems, killing them within a few days. Joseph Truini, Popular Mechanics, "How to Get Rid of Termites," 8 Jan. 2019 And your teeth are vulnerable at this moment because of a third factor: acid. Rachel Sugar, Vox, "Here is why you look like a vampire.," 18 Dec. 2018 Previous studies found that some species of bacteria and fungi did, in fact, chow down on pigments made from laccaic acid and ochres. Kiona N. Smith, Ars Technica, "What’s eating this 400-year-old painting? A whole ecosystem of microbes," 11 Dec. 2018 In a recent interview, Mulroney credited Bush with two major accomplishments: the North American Free Trade Agreement and the 1991 bilateral acid-rain treaty. Chloe Foussianes, Town & Country, "Why Brian Mulroney, Former Canadian Prime Minister, Will Speak at George H.W. Bush's Funeral," 4 Dec. 2018 Chang says to look for topical treatments that contain retinoids, hydroquinone, and azelaic acid, which have all bene proven to dramatically lighten dark marks and even melasma. Audrey Noble, Harper's BAZAAR, "How To Get Rid of Acne Scars—Forever," 21 Jan. 2019 Gentle exfoliating acids, like glycolic or alpha hydroxy acids, are an effective way to break down the dead skin and oil clogging the pore, Lily Talakoub, M.D., dermatologist at McLean Dermatology and Skincare Center in Virginia, tells SELF. Talia Abbas, SELF, "How to Get Rid of Blackheads on Your Nose, Chin and Forehead," 28 Dec. 2018 Based on her award-winning book of the same name, the show takes us to Italy, Japan, Mexico, and her home-state of California to break down just what those four elements—salt, fat, acid, and heat—mean to cooking. Condé Nast Traveler, "In Conversation With the Absolutely Delightful Samin Nosrat: Women Who Travel Podcast," 18 Dec. 2018

Recent Examples on the Web: Adjective

During the Reagan era, acid-wash jeans were, for a brief period, inescapable. Janelle Okwodu, Vogue, "Are You Ready for the Return of Acid-Wash Jeans? Katy Perry Is," 6 Aug. 2018 Vinegar contains zero calories, enhances flavor, and poses a low health risk, except for acid reflux-sufferers and diabetics. Jaclyn London, Ms, Rd, Cdn, Good Housekeeping, "The Real Benefits of Apple Cider Vinegar, According to a Nutritionist," 21 Nov. 2018 This isn’t an acid trip, or a dream, or even bad sushi. Candace Braun Davison, House Beautiful, "Amy Poehler Is 'Making It' Up As She Goes Along," 31 July 2018 The biggest issue here is acid reflux, says Dr. Mindel. Korin Miller, SELF, "7 Mistakes You Make Right Before Bed That Are Ruining Your Sleep," 28 Nov. 2018 Her long, acid-yellow hair matched her corset-style top and short-sleeved tuxedo jacket from the brand’s Yellow Label. Wendy Sy, Allure, "Celebs Are All Dyeing Their Hair Neon Colors for Fall," 14 Sep. 2018 Another common cause of chest pain is acid reflux or its more severe relative, gastroesophageal reflux disease (GERD). Cassie Shortsleeve, SELF, "Is Your Chest Pain Physical or Mental?," 14 Nov. 2018 Without proper Lyme disease treatment, the disease can linger on for years with a wide range of side effects from sore joints and memory problems to panic attacks and acid reflux, according to the International Lyme and Associated Diseases Society. Leah Zerbe, Good Housekeeping, "5 Effective Ways to Keep Ticks Out of Your Yard," 26 May 2018 In a small clinical trial, researchers randomly assigned 23 nonverbal children with autism to take folinic acid daily for 12 weeks, and 25 nonverbal children with autism to take a placebo. Nicholette Zeliadt, Washington Post, "Taking folic acid may lower the risk of autism and ease features of the condition," 2 Apr. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'acid.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of acid

Noun

1650, in the meaning defined at sense 1

Adjective

1649, in the meaning defined at sense 1a

History and Etymology for acid

Noun

borrowed from Medieval Latin acidum, going back to Latin, neuter of acidus acid entry 2

Adjective

borrowed from French & Latin; French acide, going back to Middle French, borrowed from Latin acidus, adjective derivative from the base of acēre "to be sour" — more at acetic acid

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Statistics for acid

Last Updated

19 Feb 2019

Look-up Popularity

Time Traveler for acid

The first known use of acid was in 1649

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More Definitions for acid

acid

noun

English Language Learners Definition of acid

 (Entry 1 of 2)

chemistry : a chemical with a sour taste that forms a salt when mixed with a base

acid

adjective

English Language Learners Definition of acid (Entry 2 of 2)

: of, relating to, or having the qualities of an acid
: sharp, strong, and critical in tone

acid

adjective
ac·​id | \ ˈa-səd \

Kids Definition of acid

 (Entry 1 of 2)

1 : having a taste that is sour, bitter, or stinging
2 : harsh or critical in tone acid remarks
3 : of, relating to, or like an acid an acid solution

Other Words from acid

acidly adverb spoke acidly

acid

noun

Kids Definition of acid (Entry 2 of 2)

: a chemical compound that tastes sour and forms a water solution which turns blue litmus paper red

acid

adjective
ac·​id | \ ˈas-əd \

Medical Definition of acid

 (Entry 1 of 2)

1 : sour, sharp, or biting to the taste
2a : of, relating to, or being an acid also : having the reactions or characteristics of an acid an acid solution
b of salts and esters : derived by partial exchange of replaceable hydrogen acid sodium carbonate NaHCO3
c : marked by or resulting from an abnormally high concentration of acid acid indigestion not used technically

acid

noun

Medical Definition of acid (Entry 2 of 2)

1 : a sour substance specifically : any of various typically water-soluble and sour compounds that in solution are capable of reacting with a base to form a salt, that redden litmus, that have a pH less than 7, and that are hydrogen-containing molecules or ions able to give up a proton to a base or are substances able to accept an unshared pair of electrons from a base
2 : lsd

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More from Merriam-Webster on acid

Rhyming Dictionary: Words that rhyme with acid

Thesaurus: All synonyms and antonyms for acid

Spanish Central: Translation of acid

Nglish: Translation of acid for Spanish Speakers

Britannica English: Translation of acid for Arabic Speakers

Britannica.com: Encyclopedia article about acid

Comments on acid

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