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

Some individuals—many more than have allergies to milk—are intolerant to it, meaning their bodies struggle to digest dairy products, usually due to milk sugar called lactose. —Yaakov Katz, Newsweek, 17 Jan. 2025

The company has also been sued for the upcharge on discrimination grounds because around one-third of Americans — disproportionately people of color — have difficulty digesting lactose, a sugar found in milk. —Marina Bolotnikova, Vox, 2 Nov. 2024

Consumed in excess and not broken down by enzymatic activity, lactose will ferment and cause digestive problems, inflammation and numerous symptoms (skin disorders, rhinitis, sinusitis, migraines, concentration problems, joint pain...). —Marie Bladt, Vogue, 24 Dec. 2024

There are different types of enzymes specific to different nutrients, including: protease for proteins lipase for fats lactase for lactose sucrase for sucrose How do digestive enzymes work? —Alessandra Signorelli, Vogue, 26 Nov. 2024

Word History

Etymology

International Scientific Vocabulary

First Known Use

1847, in the meaning defined above

Phrases Containing lactose

• lactose intolerant

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