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 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
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
Recent Examples on the Web
Jay R. Brooks, The Mercury News, 24 Apr. 2024
Starting with low-THC hemp, which is legal under the Farm Bill, manufacturers use acids to extract delta-8 and similar compounds from the plant.
—John Diedrich, Milwaukee Journal Sentinel | Ashley Okwuosa, The Examination | Amy Yurkanin, Al.com, Journal Sentinel, 18 Apr. 2024
Sometimes acid is needed to eat away at decades old adhesive.
—Alina Hartounian, NPR, 16 Apr. 2024
Research also shows popcorn contains phenolic acids, a type of antioxidant.
—Katie Mogg, NBC News, 14 Apr. 2024
At Kera, the chicken feathers supplied by a local farm are cleaned, pulverized and mixed with acid and keratinase – an enzyme that breaks down keratin’s strong chemical bonds.
—Leah Collins, CNN, 12 Apr. 2024
The menthol works alongside hyaluronic acid, kojic acid, vitamin B5, and centella asiatica, a powerful antioxidant that aids in healing and protecting the skin.
—Danielle Cohen, Glamour, 10 Apr. 2024
Try teal spirals or striped acid yellow tapers in silver candleholders topped with jade rings or pale blue ones that look like large format rigatoni bent into interesting shapes.
—Devra Ferst, Bon Appétit, 11 Apr. 2024
Unlike the aforementioned alpha-hydroxy acids, tranexamic acid isn't a chemical exfoliator, but a synthetic derivative of the amino acid lysine.
—Jennifer Hussein, Allure, 10 Apr. 2024
Lester Fabian Brathwaite, EW.com, 18 Apr. 2024
Sadly, this latest Scoop has none of Waugh’s acid wit or alkaline intelligence.
—Leslie Felperin, The Hollywood Reporter, 4 Apr. 2024
The jabs were sometimes playful, sometimes acid, often overstated.
—Noah Bierman, Los Angeles Times, 27 Mar. 2024
Ebb Carbon’s process makes seawater more alkaline and locks away carbon dioxide but generates some acid waste.
—IEEE Spectrum, 26 Mar. 2024
Acid reflux is what happens when acid from your stomach repeatedly rises into your esophagus.
—Daryl Austin, USA TODAY, 22 Feb. 2024
For instance, one of the key functions of the skin microbiota, which are mostly bacteria, is acid resistance.
—Sabrina Sholts, Smithsonian Magazine, 12 Mar. 2024
Freeman acquired the sculpture, which is acid bright and nearly six feet tall, from Schütte’s show that same year at Galerie Nelson in Paris.
—Travis Diehl Dean Kaufman, New York Times, 11 Mar. 2024
Kremlin spokesman Dmitry Peskov, replied with acid snark — accusing accused Kyiv of killing its own soldiers.
—Siobhán O'Grady, Washington Post, 25 Jan. 2024
Noun
The high alpha acids in hops, which are especially prominent in IPAs, can blend with capsaicin – the active component that gives chile peppers their heat – and create a feedback loop that increases the heat.
—Jay R. Brooks, The Mercury News, 24 Apr. 2024
Starting with low-THC hemp, which is legal under the Farm Bill, manufacturers use acids to extract delta-8 and similar compounds from the plant.
—John Diedrich, Milwaukee Journal Sentinel | Ashley Okwuosa, The Examination | Amy Yurkanin, Al.com, Journal Sentinel, 18 Apr. 2024
Sometimes acid is needed to eat away at decades old adhesive.
—Alina Hartounian, NPR, 16 Apr. 2024
Research also shows popcorn contains phenolic acids, a type of antioxidant.
—Katie Mogg, NBC News, 14 Apr. 2024
At Kera, the chicken feathers supplied by a local farm are cleaned, pulverized and mixed with acid and keratinase – an enzyme that breaks down keratin’s strong chemical bonds.
—Leah Collins, CNN, 12 Apr. 2024
The menthol works alongside hyaluronic acid, kojic acid, vitamin B5, and centella asiatica, a powerful antioxidant that aids in healing and protecting the skin.
—Danielle Cohen, Glamour, 10 Apr. 2024
Try teal spirals or striped acid yellow tapers in silver candleholders topped with jade rings or pale blue ones that look like large format rigatoni bent into interesting shapes.
—Devra Ferst, Bon Appétit, 11 Apr. 2024
Unlike the aforementioned alpha-hydroxy acids, tranexamic acid isn't a chemical exfoliator, but a synthetic derivative of the amino acid lysine.
—Jennifer Hussein, Allure, 10 Apr. 2024
Adjective
Young Dorothy Gale is transported, via magical tornado, to the Wonderful World of Oz, an acid trip of a town full of kindly creatures under the cruel rule of the Wicked Witch of the West.
—Lester Fabian Brathwaite, EW.com, 18 Apr. 2024
Sadly, this latest Scoop has none of Waugh’s acid wit or alkaline intelligence.
—Leslie Felperin, The Hollywood Reporter, 4 Apr. 2024
The jabs were sometimes playful, sometimes acid, often overstated.
—Noah Bierman, Los Angeles Times, 27 Mar. 2024
Ebb Carbon’s process makes seawater more alkaline and locks away carbon dioxide but generates some acid waste.
—IEEE Spectrum, 26 Mar. 2024
Acid reflux is what happens when acid from your stomach repeatedly rises into your esophagus.
—Daryl Austin, USA TODAY, 22 Feb. 2024
For instance, one of the key functions of the skin microbiota, which are mostly bacteria, is acid resistance.
—Sabrina Sholts, Smithsonian Magazine, 12 Mar. 2024
Freeman acquired the sculpture, which is acid bright and nearly six feet tall, from Schütte’s show that same year at Galerie Nelson in Paris.
—Travis Diehl Dean Kaufman, New York Times, 11 Mar. 2024
Kremlin spokesman Dmitry Peskov, replied with acid snark — accusing accused Kyiv of killing its own soldiers.
—Siobhán O'Grady, Washington Post, 25 Jan. 2024
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.
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Cite this Entry
“Acid.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/acid. Accessed 1 May. 2024.
Copy CitationKids 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 noun1
: 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 sense 3a) 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
: lsd
acid
2 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
see also acid reflux
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