The Collaborative International Dictionary of English v.0.48:

Albumin \Al*bu"min\, n. (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.
   [1913 Webster]

   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.
      [1913 Webster]

WordNet (r) 3.0 (2006):

albumin
    n 1: a simple water-soluble protein found in many animal tissues
         and liquids [syn: albumin, albumen]