Is it ensure, insure, or assure?
in biology, the general appearance of an organism as determined by the quality and quantity of light that is reflected or emitted from its surfaces. Coloration depends upon several factors: the colour and distribution of the organism's biochromes (pigments), particularly the relative location of differently coloured areas; the shape, posture, position, and movement of the organism; and the quality and quantity of light striking the organism. The perceived coloration depends also on the visual capabilities of the viewer. Coloration is a dynamic and complex characteristic and must be clearly distinguished from the concept of "colour," which refers only to the spectral qualities of emitted or reflected light.