Noun | 1. | rod cell - a visual receptor cell that is sensitive to dim light retina - the innermost light-sensitive membrane covering the back wall of the eyeball; it is continuous with the optic nerve visual cell - one of the cells of the retina that is sensitive to light retinal purple, rhodopsin, visual purple - a red photopigment in the retinal rods of vertebrates; dissociates into retinene by light |