lactic acid

noun

: a hygroscopic organic acid C3H6O3 present normally especially in muscle tissue as a by-product of anaerobic glycolysis, produced in carbohydrate matter usually by bacterial fermentation, and used especially in food and medicine and in industry

Examples of lactic acid in a Sentence

Recent Examples on the Web
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Today, this tangy beverage is made by combining lactic acid bacteria with nonfat or low-fat milk. Maxine Lipner, Verywell Health, 9 July 2025 The use of malolactic fermentation introduces lactic acid bacteria to convert harsher malic acid into softer lactic acid, enhancing roundness and balance. Felipe Schrieberg, Forbes.com, 3 July 2025 The pea-sugar beers had more lactic acid, ethanol, and flavor compounds than those brewed without them, and they were rated as having fruitier flavors and higher acidity. ArsTechnica, 2 July 2025 What other body traits attract mosquitoes? Body odor and sweat Mosquitoes are highly sensitive to body odor, particularly to compounds like lactic acid, ammonia and uric acid found in sweat, according to a post by Our Blood Institute. Brandi D. Addison, Austin American Statesman, 10 June 2025 See All Example Sentences for lactic acid

Word History

First Known Use

1790, in the meaning defined above

Time Traveler
The first known use of lactic acid was in 1790

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Cite this Entry

“Lactic acid.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lactic%20acid. Accessed 16 Jul. 2025.

Kids Definition

lactic acid

noun
lac·​tic acid
ˌlak-tik-
: an organic acid present especially in muscle tissue as a result of the breakdown of carbohydrates (as glycogen), is made from carbohydrates usually by fermentation by bacteria, and is used especially in food and medicine

Medical Definition

lactic acid

noun
: a hygroscopic organic acid C3H6O3 that is known in three optically isomeric forms:
a
or D-lactic acid : the dextrorotatory form present normally in blood and muscle tissue as a product of the anaerobic metabolism of glucose and glycogen
b
or L-lactic acid : the levorotatory form obtained by biological fermentation of sucrose
c
or DL-lactic acid : the racemic form present in food products and made usually by bacterial fermentation (as of whey or raw sugar) but also synthetically, and used chiefly in foods and beverages, in medicine, in tanning and dyeing, and in making esters for use as solvents and plasticizers

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