retinal

²ret·i·nal

noun \ˈret-^ən-ˌal, -ˌȯl\

Definition of RETINAL

: a yellowish to orange aldehyde C₂₀H₂₈O derived from vitamin A that in combination with proteins forms the visual pigments of the retinal rods and cones—called also retinene, retinene₁, vitamin A aldehyde