The phrase monochromatic or monochromatic colors refers to a single hue in a color palette that is expanded upon by adding two, three, or more shade or tints (variations in lightness and saturation) of that color, to create a more balanced look.
Compare to monochrome, which means one color. Typically one color is presented in different values and intensities or different shades of the single color.
In desktop publishing using monochromatic colors is a technique used to vary color in the print document without paying to add additional colors.
Read more resources on monochromatic colors.
Recommended Reading: Webopedia’s monochrome and color wheel definitions.