Princeton's WordNet(0.00 / 0 votes)Rate this definition: 1  shimmer, play(verb) a weak and tremulous light. 2  shimmer(verb) shine with a weak or fitful light. 3  shimmer(verb) give off a shimmering reflection, as of silk.
Cats, like humans, have both rods and cones in the retina. Rods are the receptors that the eye uses for night time viewing and sudden movement. Cones are used during the daytime, and process color information. Cats have more rods than cones, as compared with humans, making cat night vision superior to humans.
Cones. Cones are the cells capable of color vision and responsible for high spatial acuity. Unlike the rods, cones do not have individual disks to hold the photochemicals. Photochemicals are in the outer membrane of the cell, and the shape of the cone is determined by folding of the outer membrane.