Art Glossary: Chroma

Definition:

The chroma of a color is a measure of how pure or intense it is, how saturated the color is. You reduce the chroma of a paint color by adding a neutral gray with the identical value as the color you're wanting to change.

Colors have three attributes -- hue, value, and chroma. In non-art speak terms, these are generally simply called color, darkness/lightness, and intensity/saturation.