\Xan"thin\, n. [Gr. xanqo`s yellow.]
1. (Physiol. Chem.) A crystalline nitrogenous body closely
   related to both uric acid and hypoxanthin, present in
   muscle tissue, and occasionally found in the urine and in
   some urinary calculi. It is also present in guano. So
   called from the yellow color of certain of its salts
   (nitrates).

2. (Chem.) A yellow insoluble coloring matter extracted from
   yellow flowers; specifically, the coloring matter of
   madder. [Formerly written also {xanthein}.]

3. (Chem.) One of the gaseous or volatile decomposition
   products of the xanthates, and probably identical with
   carbon disulphide. [Obs.]