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

Buttermilk or Yogurt Buttermilk and yogurt contain lactic acid, which can help exfoliate and lighten pigmentation. —Heather Jones, Verywell Health, 16 June 2025

This sunscreen is non-comedogenic and features lactic acid and niacinamide for anti-inflammatory and oil production benefits. —Jenny Berg, Vogue, 13 June 2025

This natural process occurs when enzymes break down the sugars in the vegetables, producing lactic acid as a byproduct.4 They Both Have Gut Health Benefits Because of their rich probiotic content, both kimchi and sauerkraut may help balance your gut microbiome. —Lauren Manaker Ms, Health, 11 June 2025

Go with the combo of glycerin, hyaluronic acid, lactic acid, and shea butter found in the legendary Magic Cream from Charlotte Tilbury. —Denise Primbet, Glamour, 28 May 2025

Word History

First Known Use

1790, in the meaning defined above

Rhymes for lactic acid

• antacid
• placid

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