<p><strong>Noun</strong></p><ul><li>Biochemistry. A disaccharide, C₁₂H₂₂O₁₁, present in milk, that upon hydrolysis yields glucose and galactose.</li><li>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.</li></ul>