lactose

noun

lac·tose ˈlak-ˌtōs

-ˌtōz

: a disaccharide sugar C₁₂H₂₂O₁₁ that is present in milk and yields glucose and galactose upon hydrolysis and yields especially lactic acid upon fermentation

Examples of lactose in a Sentence

Recent Examples on the Web Josh Belinsky, the 28-year-old who’s got milk —minus the lactose. —

Chloe Sorvino, Forbes, 28 Nov. 2023 Lactose Intolerance About 65% of people worldwide cannot digest lactose properly. —

Amanda Gardner, Health, 29 Oct. 2023 Bacteria are then added and start fermentation by turning lactose into lactic acid. —

Elizabeth Rayne, Ars Technica, 14 Oct. 2023 Whey protein powder, for example, may contain lactose. —

Colleen De Bellefonds, Women's Health, 30 Aug. 2023 And depending on the brand and how it’s made, some whey protein powders may end up with more lactose than others. —

Amy Marturana Winderl, SELF, 19 Sep. 2023 In populations of people with a history of cattle domestication, adults generally have the ability to digest lactose, whereas in most groups globally, lactose digestion declines after waning. —

Conor Feehly, Discover Magazine, 9 Mar. 2023 A lot of people have trouble digesting and absorbing lactose; some estimates suggest that this is the case for up to 68% of the world’s population. —

Amy Marturana Winderl, SELF, 19 Sep. 2023 In addition, people with allergies to components found in colostrum, such as proteins or lactose, may experience reactions. —

Sandra Rose Salathe, Peoplemag, 11 Sep. 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'lactose.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

International Scientific Vocabulary

First Known Use

1847, in the meaning defined above

Time Traveler

The first known use of lactose was in 1847

See more words from the same year

Cite this Entry

Style

“Lactose.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lactose. Accessed 7 Dec. 2023.

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Kids Definition

lactose

noun

lac·tose ˈlak-ˌtōs

: a sugar present in milk that breaks down to give glucose and galactose and on fermentation gives especially lactic acid

called also milk sugar

Medical Definition

lactose

noun

lac·tose ˈlak-ˌtōs, -ˌtōz

: a disaccharide sugar C₁₂H₂₂O₁₁ that is present in milk, yields glucose and galactose upon hydrolysis, yields especially lactic acid upon fermentation, and is used chiefly in foods, medicines, and culture media (as for the manufacture of penicillin)

called also milk sugar