Chlorophyll \Chlo"ro*phyll\, n. [Gr. ? light green + ? leaf: cf. F. chlorophylle.]

(Bot.) Literally, leaf green; a green granular matter formed in the cells of the leaves (and other parts exposed to light) of plants, to which they owe their green color, and through which all ordinary assimilation of plant food takes place. Similar chlorophyll granules have been found in the tissues of the lower animals. [Written also chlorophyl.]

Source: Webster's Revised Unabridged Dictionary (1913)