mannitol A polyhydric alcohol, CH₂OH(CHOH)₄CH₂OH, derived from mannose or fructose. It is the main soluble sugar in fungi and an important carbohydrate reserve in brown algae. Mannitol is used as a sweetener in certain foodstuffs and as a diuretic in medicine to relieve fluid retention.

mannitol Mannite or manna sugar, a six‐carbon sugar alcohol found in beets, pumpkin, mushrooms, onions; 50–60% as sweet as sucrose. Extracted commercially from seaweed (Laminaria spp.) or made from the sugar mannose (E‐421).

mannitol A polyhydroxy alcohol, which can be synthesized chemically by the reduction of mannose. It is found in many higher plants and in some algae.

mannitol (man-i-tol) n. a diuretic administered by intravenous infusion mainly to reduce intracranial pressure in brain injuries, and in the emergency treatment of glaucoma.