Sugar  —n. 1 sweet crystalline substance esp. From sugar cane and sugar beet, used in cookery etc.; sucrose. 2 chem. Soluble usu. Sweet crystalline carbohydrate, e.g. Glucose. 3 esp. Us colloq. Darling (as a term of address). —v. Sweeten or coat with sugar. [french sukere, from arabic sukkar]