Copy Citation
Test your vocabulary with our 10-question quiz!
TAKE THE QUIZ1
: 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 6a) 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
acidy
adjective
ˈa-sə-dē
1
a
: 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
2
a
: 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
acidly
adverb
acidness
noun
Synonyms
Example Sentences
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
Recent Examples on the Web
Melanie Rud, SELF, 16 Mar. 2023
Meanwhile, compostable options featuring polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT) are generally in tea bags, magazine wrappings, and coffee cup lids.
—Andrew Paul, Popular Science, 14 Mar. 2023
Mashed potatoes are one of my favorite comfort foods, and the sausage/apple/onion mixture is a nice combination of sweet and savory, with a bit of acid from the vinegar for balance.
—Bon Appétit Contributor, Bon Appétit, 10 Mar. 2023
Return to menu One of my favorite ways to perk up a bland dish is with a splash of acid.
—Becky Krystal, Washington Post, 6 Mar. 2023
Doctors already prescribe the drug, known chemically as bempedoic acid, to be used together with a statin to help certain high-risk patients further lower their cholesterol.
—Lauran Neergaard, ajc, 4 Mar. 2023
In one nail-biting scene, Maurice takes an inflatable raft out on a sulfuric acid lake in Indonesia but quickly abandons his mission as acid starts chewing through the boat.
—Patrick Ryan, USA TODAY, 9 Feb. 2023
Looking at mouse, pig, and human hearts, the researchers found that valproic acid promotes the activity of a gene called IRG1, which produces a substance called itaconate that has anti-inflammatory and antioxidant effects.
—Elaine Chen, STAT, 8 Feb. 2023
Sandoval whips in pickled mustards, adding texture and tiny pops of acid.
—Los Angeles Times, 30 Jan. 2023
Chris Wiley, The New Yorker, 13 Feb. 2023
In the trailer, the singer wears an acid green fur coat from AREA's fall winter 2022 runway.
—Chelsey Sanchez, Harper's BAZAAR, 13 Jan. 2023
One is a large vertical composition from the early 1960s that depicts a swimming beach in Maine with pine trees and puffy clouds rising beyond a crescent of purple sand that edges a cove painted in jarringly acid tones of yellow-green and turquoise.
—Steven Litt, cleveland, 8 Jan. 2023
The cafe is a project of the Chhanv Foundation, a nonprofit organization in India working for the rehabilitation of acid attack survivors.
—Saqib Mugloo, The Christian Science Monitor, 15 Feb. 2023
For the person who is ready for morning 5Ks around their neighborhood, the Adidas Supernova+ running shoes in black and acid red are marked down to under $100.
—Elizabeth Djinis, SELF, 15 July 2022
Successful treatments may be due to enzymatic, polyphenolic, or acid deodorization.
—Seriously Science, Discover Magazine, 16 Apr. 2017
Night sweats have been observed as a manifestation to the burning sensation of acid reflux, according to a 2020 study.
—Women's Health, 2 Feb. 2023
In 2018, elevated levels of the cancer causing compound NDMA were found in drugs used to control high blood pressure, heart failure, heartburn, acid reflux as well as diabetes.
—Jen Christensen, CNN, 19 Jan. 2023
See More
Noun
Fermentation is a chemical process during which starches or sugars are converted into an alcohol or acid, via enzymes from some type of microorganism.
—Melanie Rud, SELF, 16 Mar. 2023
Meanwhile, compostable options featuring polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT) are generally in tea bags, magazine wrappings, and coffee cup lids.
—Andrew Paul, Popular Science, 14 Mar. 2023
Mashed potatoes are one of my favorite comfort foods, and the sausage/apple/onion mixture is a nice combination of sweet and savory, with a bit of acid from the vinegar for balance.
—Bon Appétit Contributor, Bon Appétit, 10 Mar. 2023
Return to menu One of my favorite ways to perk up a bland dish is with a splash of acid.
—Becky Krystal, Washington Post, 6 Mar. 2023
Doctors already prescribe the drug, known chemically as bempedoic acid, to be used together with a statin to help certain high-risk patients further lower their cholesterol.
—Lauran Neergaard, ajc, 4 Mar. 2023
In one nail-biting scene, Maurice takes an inflatable raft out on a sulfuric acid lake in Indonesia but quickly abandons his mission as acid starts chewing through the boat.
—Patrick Ryan, USA TODAY, 9 Feb. 2023
Looking at mouse, pig, and human hearts, the researchers found that valproic acid promotes the activity of a gene called IRG1, which produces a substance called itaconate that has anti-inflammatory and antioxidant effects.
—Elaine Chen, STAT, 8 Feb. 2023
Sandoval whips in pickled mustards, adding texture and tiny pops of acid.
—Los Angeles Times, 30 Jan. 2023
Adjective
In the years since, Carey has continued to mine this neo-modernist vein, adding splashes of acid color to her initially sober palette, smearing and stretching the Polaroid chemistry to unique effect.
—Chris Wiley, The New Yorker, 13 Feb. 2023
In the trailer, the singer wears an acid green fur coat from AREA's fall winter 2022 runway.
—Chelsey Sanchez, Harper's BAZAAR, 13 Jan. 2023
One is a large vertical composition from the early 1960s that depicts a swimming beach in Maine with pine trees and puffy clouds rising beyond a crescent of purple sand that edges a cove painted in jarringly acid tones of yellow-green and turquoise.
—Steven Litt, cleveland, 8 Jan. 2023
The cafe is a project of the Chhanv Foundation, a nonprofit organization in India working for the rehabilitation of acid attack survivors.
—Saqib Mugloo, The Christian Science Monitor, 15 Feb. 2023
For the person who is ready for morning 5Ks around their neighborhood, the Adidas Supernova+ running shoes in black and acid red are marked down to under $100.
—Elizabeth Djinis, SELF, 15 July 2022
Successful treatments may be due to enzymatic, polyphenolic, or acid deodorization.
—Seriously Science, Discover Magazine, 16 Apr. 2017
Night sweats have been observed as a manifestation to the burning sensation of acid reflux, according to a 2020 study.
—Women's Health, 2 Feb. 2023
In 2018, elevated levels of the cancer causing compound NDMA were found in drugs used to control high blood pressure, heart failure, heartburn, acid reflux as well as diabetes.
—Jen Christensen, CNN, 19 Jan. 2023
See More
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'acid.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Word History
Etymology
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
Phrases Containing acid
Articles Related to acid
Dictionary Entries Near acid
Cite this Entry
“Acid.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/acid. Accessed 30 Mar. 2023.
Kids Definition
acid
2 of 2 noun1
: a sour substance
2
: a compound that usually dissolves in water, has a sour taste, reacts with a base to form a salt, and turns litmus paper red
3
: lsd
Medical Definition
acid
1 of 2 adjective
ac·id
ˈas-əd 
1
: sour, sharp, or biting to the taste
2
a
: 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
2 of 2 noun1
: 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
More from Merriam-Webster on acid
Nglish: Translation of acid for Spanish Speakers
Britannica English: Translation of acid for Arabic Speakers
Britannica.com: Encyclopedia article about acid
Love words? Need even more definitions?
Merriam-Webster unabridged
Words at Play
Ask the Editors
Word Games
-
Name That Flower
Can you tell the difference between a lilac and a...
Take the quiz
-
Are You Feeling Lucky?
A charming quiz about fortunate and unfortunate w...
Take the quiz
-
How Strong Is Your Vocabulary?
Test your vocabulary with our 10-question quiz!
Take the quiz
-
Spelling Bee Quiz
Can you outdo past winners of the National Spelli...
Take the quiz
Share