Source : Webster's Revised Unabridged Dictionary (1913)

Cystine \Cyst"ine\ (s?s"t?n; 104), n. [See {Cyst}.] (Physiol.
   Chem.)
   A white crystalline substance, {C3H7NSO2}, containing
   sulphur, occuring as a constituent of certain rare urinary
   calculi, and occasionally found as a sediment in urine.

Source : WordNet®

cystine
     n : a crystalline amino acid found in proteins (especially
         keratin); discovered in bladder stones