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

Additionally, this hyaluronic acid serum also includes lactic acid, which helps reduce acne breakouts and reduce the appearance of blemishes for an overall smoother complexion. —Jessie Quinn, People.com, 1 Nov. 2024

Designed for daytime and nighttime use, the formulation also has lactic acid—the exfoliating alpha-hydroxy acid increases the cream’s absorption, bolsters the antioxidant properties of vitamin C, and unclogs the pores. —Jenny Berg, Vogue, 31 Oct. 2024

Those acids include gentle alpha-hydroxy lactic acid as well as gluconolactone, a polyhydroxy acid that mildly resurfaces as well as helps to hydrate the skin. —Emily Orofino, Allure, 29 Oct. 2024

The lactic acid bacteria found in buttermilk are largely responsible for buttermilk's distinctive flavor. —Liv Dansky, Southern Living, 13 Oct. 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