(n.) The number of distinct colors that can be represented by a piece of hardware or software. Color depth is sometimes referred to as bit depth because it is directly related to the number of bits used for each pixel. A 24-bit video adapter, for example, has a color depth of 2 to the 24th power (about 16.7 million) colors. One would say that its color depth is 24 bits.
Color depth is also referred to as bits per pixel (bpp).
Video Modes, Resolution and Color Describes the technical details of video modes and signals, as well as the major characteristics of the video image. This page is from "The PC Guide."
