What term refers to the degree of lightness or darkness of a color?

The term that refers to the degree of lightness or darkness of a color is value. In color theory, value determines how light or dark a color appears, which can affect the perception and mood of the design. It is important in creating depth, contrast, and emphasis in visual compositions.

Chroma refers to the purity or intensity of a color, saturation describes the vividness of a color versus its grayness, and hue indicates the aspect of color that allows us to classify it as red, blue, yellow, etc. While all these terms describe important properties of color, value specifically addresses the lightness or darkness component, making it the correct choice for this question.