lac·​tose | \ ˈlak-ˌtōs How to pronounce lactose (audio) , -ˌtōz \

Definition of lactose

: 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 It's brewed with lactose, honey, blueberry and blackberry puree, berry essence and vanilla essence, and has a 6.5% ABV. Carol Deptolla, Milwaukee Journal Sentinel, 5 June 2021 Although there are no specific tests to identify what foods trigger symptoms, people with IBS-D often find that foods containing lactose or gluten are problematic and that avoiding those can provide some relief. Claire Gillespie,, 5 May 2021 Brewed with pineapple and lactose as well as Simcoe, Azzacca and Amarillo hops. Marc Bona, cleveland, 2 May 2021 The soft serve at Yoga-urt is made with almonds and cashews, allowing even the most lactose-intolerant among us to indulge. Los Angeles Times, 27 Apr. 2021 Be sure to add only non-fat, non-GMO, organic, lactose-free milk! Steve Bender, Southern Living, 23 Apr. 2021 One week out of the month, there's a lactose-free soft serve, and the remaining three weeks are reserved for a dairy-free option. Rick Nelson, Star Tribune, 26 Mar. 2021 This digestive issue results from an inability to fully digest lactose, according to the NIDDK. Melissa Matthews, SELF, 5 Jan. 2021 Lactose intolerance happens when someone isn't able to completely digest the lactose, or sugar, in dairy products like milk and certain cheeses, the National Institute of Diabetes and Digestive and Kidney Disorders (NIDDK) explains. Melissa Matthews, SELF, 5 Jan. 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lactose.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of lactose

1847, in the meaning defined above

History and Etymology for lactose

International Scientific Vocabulary

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Time Traveler for lactose

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The first known use of lactose was in 1847

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Last Updated

12 Jun 2021

Cite this Entry

“Lactose.” Dictionary, Merriam-Webster, Accessed 21 Jun. 2021.

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More Definitions for lactose



English Language Learners Definition of lactose

chemistry : a type of sugar that is present in milk


lac·​tose | \ ˈlak-ˌtōs How to pronounce lactose (audio) \

Kids Definition of lactose

: a sugar that is found in milk


lac·​tose | \ ˈlak-ˌtōs, -ˌtōz How to pronounce lactose (audio) \

Medical Definition of lactose

: 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

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