Glycogen :: Glycogen (n.) A white, amorphous, tasteless substance resembling starch, soluble in water to an opalescent fluid. It is found abundantly in the liver of most animals, and in small quantity in other organs and tissues, particularly in the embryo. It is quickly changed into sugar when boiled with dilute sulphuric or hydrochloric acid, and also by the action of amylolytic ferments..