- (chemistry) 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.
- A white waxy substance found in the sap of the South American cow tree (Galactodendron).
- An amorphous, gummy carbohydrate resembling gelose, found in the seeds of leguminous plants, and yielding on decomposition several sugars, including galactose.
Ancient Greek milk. Compare lactin.