yellow pigment found in plants.
Merriam-Webster Online Dictionary
xanthophyll (noun) any of several yellow to orange carotenoid pigments that are oxygen derivatives of carotenes , especially - lutein
xanthophyll (Wikipedia)
The characteristic color of egg yolk indicates the presence of lutein, and is the typical color of lutein or zeaxanthin of the xanthophylls, a division of the carotenoids group.
Xanthophylls (originally phylloxanthins) are yellow pigments that occur widely in nature and form one of two major divisions of the carotenoid group; the other division is formed by the carotenes. The name is from Greek xanthos (ξανθός, "yellow") and phyllon (φύλλον, "leaf"), due to their formation of the yellow band seen in early chromatography of leaf pigments.