color 1. the quality of an object or substance with respect to light reflected by the object, usually determined visually by measurement of hue, saturation, and brightness of the reflected light; saturation or chroma; hue. 2. the natural appearance of the skin, esp. of the face; complexion: She has a lovely color. 3. a ruddy complexion: the wind and sun had given color to the sailor's face. 4. a blush: His remarks brought the color to her face. 5. vivid or distinctive quality, as of a literary work: Melville's description of a whaling voyage is full of color. (Webster's. p 406)
color, hue; tint, tinct, tincture, tinge, shade, tone, cast; key; coloring, coloration; color harmony, color balance, color scheme; decorator color; complexion, skin color or coloring or tone; chromatism, chromism; achromatism; natural color; undercolor; pallor; -chroia, -chromasia, chrom(o)-, chromat(o)-, -chrome, -chromia, -chromy (Chapman, p 264)
Color is a tool that has very powerful effects on visual presentations. The following links gives specific information about color theory and use for both Web and print presentations.
Color Matters - Design-Art - Color Theory - Provides an introduction and a few basic concepts regarding color theory that encompasses a multitude of definitions, concepts and design applications. All the information would fill several encyclopedias.