The Collaborative International Dictionary of English v.0.48:

Xanthophyll \Xan"tho*phyll\, n. [Xantho- + Gr. fy`llon leaf.]
   (Bot.)
   A yellow coloring matter found in yellow autumn leaves, and
   also produced artificially from chlorophyll; -- formerly
   called also phylloxanthin.
   [1913 Webster]

WordNet (r) 3.0 (2006):

xanthophyll
    n 1: yellow carotenoid pigments in plants and animal fats and
         egg yolks [syn: xanthophyll, xanthophyl, lutein]