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

Can Lead to Better Digestion The lactic acid bacteria in sourdough break down non-digestible carbohydrates in flour.2 FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) are short-chain carbohydrates that are poorly absorbed in the small intestine. —Elizabeth Barnes, Verywell Health, 13 Dec. 2024

There's no need to worry about the wash drying out your skin either, thanks to moisturizing and exfoliating ingredients, including glycerin and lactic acid. —Deanna Pai, Allure, 13 Dec. 2024

The cream can be used day and night, but be sure to pair it with SPF by day as lactic acid can make the skin more sensitive to sun damage. —Jenny Berg, Vogue, 31 Oct. 2024

Avoid ingredients like alcohol, camphor, glycolic acid, fragrances, lactic acid, menthol, sodium lauryl sulfate, or urea. —Mark Gurarie, Verywell Health, 2 Dec. 2024

Word History

First Known Use

1790, in the meaning defined above

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

ˈdē- 

: 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

ˈel- 

: the levorotatory form obtained by biological fermentation of sucrose

c

or DL-lactic acid

ˈdē-ˈel- 

: 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