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.
CONE CELLS are the second type of light sensitive cells in the retina of the eye. The human retina contains 6-7 million cones; they function best in bright light and are essential for acute vision (receiving a sharp accurate image).
However, they are not sensitive to color. The 6 to 7 million cones provide the eye's color sensitivity and they are much more concentrated in the central yellow spot known as the macula. In the center of that region is the  fovea centralis , a 0.3 mm diameter rod-free area with very thin, densely packed cones.owever, they are not sensitive to color. The 6 to 7 million cones provide the eye's color sensitivity and they are much more concentrated in the central yellow spot known as the macula. In the center of that region is the  fovea centralis , a 0.3 mm diameter rod-free area with very thin, densely packed cones.