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

In the final step, the bacteria swallow up the phenylacetic acid as an energy source. Jonathon Keats, Discover Magazine, "Bacteria That Eat Drugs Could Help Solve the Antibiotic Resistance Crisis," 8 Nov. 2018 Next up, the acids in plaque attack minerals in the protective, hard enamel surface of your teeth, which leads to holes, the Mayo Clinic explains. Korin Miller, SELF, "Is It Actually Possible to Get Rid of Cavities Without Fillings?," 17 Oct. 2018 Juul uses benzoic acid, though their patent covers a wide range of other acids as well. Rachel Becker, The Verge, "Juul’s nicotine salts are dominating the market — and other companies want in," 21 Nov. 2018 Standouts include a fantastic flamingo pink cropped fur Gucci chubbie, an acid green terry cloth polo, a gorgeous python skin jacket, and a scintillating leopard print wrap top and skirt set. Monica Kim, Vogue, "James Veloria Christens JV Retreat—A Red Hot Vintage Playroom—With a ’90s Tom Ford Sale," 15 Nov. 2018 Acid reflux happens when stomach acid reverses into your esophagus, creating symptoms like chest pain, heartburn, problems swallowing, a lump in your throat, and more, according to the Mayo Clinic. Cassie Shortsleeve, SELF, "Is Your Chest Pain Physical or Mental?," 14 Nov. 2018 But the meteor also could have sentenced the dinosaurs to extinction by kicking up a huge amount of dust and other particles, causing a temporary dimming of the sun and global cooling, and generating acid rainfall. Katherine Long, The Seattle Times, "UW’s new provost plumbs one of Earth’s most fascinating mysteries," 22 Oct. 2018 The gardener — seeing results but not entirely satisfied — often trades up to higher concentrations, replacing household vinegar (5% acetic acid) with a horticultural product (typically 20%). Margaret Roach, Good Housekeeping, "Why It Can Be Dangerous to Use Vinegar to Kill Weeds," 15 Aug. 2018 There was a distinct air of rebellion, with lots of acid-bright shades of pink (as seen on Halsey’s perpetually statement-making crop), yellow, and green adding to the vast spectrum of colors. Lauren Valenti, Vogue, "Eye-Popping Hair Rules the Street at Tokyo Fashion Week," 19 Oct. 2018

Recent Examples on the Web: Adjective

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 One out of five Americans suffers from gastroesophageal reflux disease, aka GERD or acid reflux. Jill Provost, Woman's Day, "End Digestive Problems for Good," 21 May 2012 The serum promised the same kind of results, thanks to a blend of arginine, acid proteins, and Pro Vitamin B5. Jenna Rosenstein, Harper's BAZAAR, "I Tried The Easy (and Longer Lasting) Alternative to Fake Lashes," 9 Oct. 2018 In 2017, there were more than 500 acid attacks reported across the region. Ryan Gaydos, Fox News, "Father of 3-year-old UK boy charged in apparent acid attack, due in court with 5 other suspects," 28 Aug. 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

10 Dec 2018

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

adjective

English Language Learners Definition of acid

 (Entry 1 of 2)

: of, relating to, or having the qualities of an acid

: sharp, strong, and critical in tone

acid

noun

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

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

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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