1. (mannitol) A polyhydroxy alcohol (sugar alcohol), C6H8(OH)6, produced by many vascular plants and some algae. It is a white, crystalline solid, first obtained from an ash tree (Fraxinus ornus) resembling the biblical food, hence its name.
2. According to the Bible and Koran, a food that God provided for the Israelites to sustain them during their travels across the desert. There are several speculations about its identity.