The Collaborative International Dictionary of English v.0.48:

Globulin \Glob"u*lin\, n. [From Globule: cf. F. globuline.]
   (Phisiol. Chem.)
   An albuminous body, insoluble in water, but soluble in dilute
   solutions of salt. It is present in the red blood corpuscles
   united with h[ae]matin to form h[ae]moglobin. It is also
   found in the crystalline lens of the eye, and in blood serum,
   and is sometimes called crystallin. In the plural the word is
   applied to a group of proteid substances such as vitellin,
   myosin, fibrinogen, etc., all insoluble in water, but soluble
   in dilute salt solutions.
   [1913 Webster]

WordNet (r) 3.0 (2006):

globulin
    n 1: a family of proteins found in blood and milk and muscle and
         in plant seed