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

The bacteria, known as a yogurt culture, ferments the natural sugar lactose, which produces the creamy, tangy texture and flavor of yogurt. —Allison Herries, Verywell Health, 10 Feb. 2025

While cream is not toxic to cats, many adult cats are lactose intolerant, meaning their digestive systems cannot properly process the lactose in dairy products. —Justin Gest, Newsweek, 20 Jan. 2025

Minimal Lactose Ghee is also nearly free from lactose, a milk sugar that can cause digestive symptoms in many people. —Jillian Kubala, Health, 15 Jan. 2025

With less lactose than regular, unstrained yogurts, both Greek yogurt and skyr might be suitable for some people with lactose intolerance, but not necessarily for all. —Lauren O'Connor, Ms, Health, 3 Feb. 2025

Word History

Etymology

International Scientific Vocabulary

First Known Use

1847, in the meaning defined above

Phrases Containing lactose

• lactose intolerant

Rhymes for lactose

• galactose

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