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.