mannitol Syllabification: (man·ni·tol)Pronunciation: /ˈmanəˌtôl, -ˌtäl/Definition of mannitol noun Chemistry a colorless sweet-tasting crystalline compound that is found in many plants and is used in various foods and medical products. An alcohol; chemical formula: CH2OH(CHOH)4CH2OH Origin: late 19th century: from mannite, in the same sense, + -olmannitol in other Oxford dictionaries Definition of mannitol in the British & World English dictionary