(Chem.) A thick, viscous nitrogenous substance, which is the chief and characteristic constituent of white of eggs and of the serum of blood, and is found in other animal substances, both fluid and solid, also in many plants. It is soluble in water and is coagulated by heat and by certain chemical reagents. Acid albumin, a modification of albumin produced by the action of dilute acids. It is not coagulated by heat. - Alkali albumin, albumin as modified by the action of alkaline substances; - called also albuminate.