The Collaborative International Dictionary of English v.0.48:

Euxanthic \Eux*an"thic\a. (Chem.)
   Having a yellow color; pertaining to, derived from, or
   resembling, euxanthin.
   [1913 Webster]

   Euxanthic acid (Chem.), a yellow, crystalline, organic
      acid, extracted from euxanthin.
      [1913 Webster]