lactose

n. disaccharide in milk which yields glucose and galactose when hydrolyzed; white crystalline substance obtained from milk, milk sugar

Lactose is a disaccharide that consists of β-D-galactose and β-D-glucose molecules bonded through a β1-4 glycosidic linkage. Lactose makes up around 2-8% of the solids in milk. The name comes from the Latin word for milk, plus the -ose ending used to name sugars.
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Lactose /lac·tose/ a disaccharide occurring in mammalian milk, which on hydrolysis yields glucose and galactose; used as a tablet and capsule [more]Lactose - Community and Resources

Noun
1. a sugar comprising one glucose molecule linked to a galactose molecule; occurs only in milk; "cow's milk contains about 4.7% lactose"
(synonym) milk sugar
(hypernym) disaccharide

n. lactose, disaccharide in milk which yields glucose and galactose when hydrolyzed, white crystalline substance obtained from milk, milk sugar