lactose

/ˈlæktoʊs/

/ˈlæktəʊs/

Lactose is the kind of sugar that's found in milk and other foods made from milk. Some people have trouble digesting lactose and avoid eating dairy products. No cheese stick for you!

You might learn about lactose in chemistry class, including the fact that it's made of two sugars, glucose and galactose. Lactose is broken down into these simpler sugars by lactase, an enzyme that most of us have plenty of. However, if you're one of the people without enough lactase, eating food with lactose can be unpleasant. The lacto- comes from the Latin lac, or "milk," and the chemical suffix -ose tells you it's a sugar.

Definitions of lactose

1. noun

   a sugar comprising one glucose molecule linked to a galactose molecule; occurs only in milk
   “cow's milk contains about 4.7% lactose”

   synonyms: milk sugar

   type of:

   disaccharide

   any of a variety of carbohydrates that yield two monosaccharide molecules on complete hydrolysis