[f. L. lact-, lac + -OSE2. Cf. F. lactose.] A saccharine substance present in milk, commonly called sagar of milk.
1858. Fownes’ Chem. (ed. 7), 410. Sugar of milk; lactin; lactose.
1869. Roscoe, Elem. Chem., 396. Lactose, or milk sugar, occurs only in the milk of mammalia.
