Galactin \Ga*lac"tin\, n. [Gr. ?, ?, milk. Cf. {Lactin}.] (Chem.) (a) An amorphous, gelatinous substance containing nitrogen, found in milk and other animal fluids. It resembles peptone, and is variously regarded as a coagulating or emulsifying agent. (b) A white waxy substance found in the sap of the South American cow tree ({Galactodendron}). (c) An amorphous, gummy carbohydrate resembling gelose, found in the seeds of leguminous plants, and yielding on decomposition several sugars, including galactose.