Source : Webster's Revised Unabridged Dictionary (1913)

Alizarin \A*liz"a*rin\, n. [F. alizarine, fr. alizari.] (Chem.)
   A coloring principle, {C14H6O2(OH)2}, found in madder, and
   now produced artificially from anthracene. It produces the
   Turkish reds.

Source : WordNet®

alizarin
     n : an orange-red crystalline compound used in making red
         pigments and in dyeing [syn: {alizarine}]