American Heritage® Dictionary of the English Language, Fourth
Edition - n. Any of a class of yellow to red pigments, including
the carotenes and the xanthophylls. - adj. Of or relating to
such a pigment. - n. organic chemistry Any of a class of yellow
to red plant pigments including the carotenes and xanthophylls.
- adj. organic chemistry Of, or relating to such a class of
pigments. - n. any of a class of highly unsaturated yellow to
red pigments occurring in plants and animals “He was soon drawn
deeply into studies of how the small variations in carotenoid
structures are involved in biological functions.” “It starts
with shorter days, which triggers a whole series of processes,
says Ed Hedborn, a botanist who manages plant records at the
Morton Arboretum outside Chicago in Lisle, Ill. With less
daylight, trees and other plants stop making chlorophyll, whose
absence unmasks the yellow, orange and brown hues of the pigment
carotenoid, which is always in the leaves, but hidden by the
green.” “Carotenoids are a