The Collaborative International Dictionary of English v.0.48:

Amidin \Am"i*din\, n. [Cf. F. amidine, fr. amido? starch, fr. L.
   amylum, Gr. ? fine meal, neut. of ? not ground at the mill,
   -- hence, of the finest meal; 'a priv. + ?, ?, mill. See
   Meal.] (Chem.)
   Start modified by heat so as to become a transparent mass,
   like horn. It is soluble in cold water.
   [1913 Webster]