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 How to pronounce acid (audio) \

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

Champagne is usually made from grapes picked early in the season, when there is less sugar in the fruit and higher levels of acid. Jennifer Ouellette, Ars Technica, "The secret to champagne’s universal appeal is the physics of bubbles," 31 Dec. 2018 Step 2: Treatment For dry skin, there are a number of ways to soothe parched complexions (i.e. amping up your antioxidant intake and reducing the number of acids in your routine). Allison Duncan, Allure, "How to Tell If Your Skin Is Dry or Dehydrated, According to Experts," 22 Aug. 2018 In slinky Rick Owens tank top and latex skirt, both in shades of acid green, Kardashian pulled off a tricky hue while testing out her latest it accessory. Janelle Okwodu, Vogue, "Kim Kardashian Makes it Official: Sporty Shield Sunglasses are the Shape of the Moment," 8 Aug. 2018 Things heated up yesterday when one driver was beaten unconscious and another was taken to the hospital with first-degree burns after an acid attack, according to the Associated Press. Meredith Carey, Condé Nast Traveler, "You Can't Use Uber in Barcelona Right Now," 26 July 2018 Semen contains components like sugars, enzymes, and acids, all of which can irritate your fragile ocular tissue. Kasandra Brabaw, SELF, "So, You Got Semen in Your Eye. Here's What to Do," 1 Mar. 2019 To go along with the einkorn pollen, Maixner and his colleagues’ chemical analysis found a compound called azelaic acid, which usually shows up in whole grain cereals. Kiona N. Smith, Ars Technica, "Ötzi the Iceman’s last meal shows how Copper Age people ate on the run," 13 July 2018 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

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 Mar 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 How to pronounce acid (audio) \

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 How to pronounce acid (audio) \

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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