ˈret ə nˌēn noun
( -s )
Etymology: retin- (II) + -ene
: either of two carotenoid pigments that are aldehydes corresponding to the two vitamin A alcohols from which they are formed reversibly by oxidation:
a. : a light yellow crystalline compound C 19 H 27 CHO related to vitamin A 1 and formed from rhodopsin or iodopsin by the action of light — called also retinene 1
b. : an orange-red crystalline compound C 19 H 25 CHO related to vitamin A 2 and formed from porphyropsin by the action of light — called also retinene 2