/lak"tohs/ , n.
1. Biochem. a disaccharide, C 12 H 22 O 11 , present in milk, that upon hydrolysis yields glucose and galactose.
2. a white, crystalline, sweet, water-soluble commercial form of this compound, obtained from whey and used in infant feedings, in confections and other foods, in bacteriological media, and in pharmacology as a diluent and excipient. Also called milk sugar, sugar of milk .
[ 1855-60; LACT- + -OSE 2 ]