What term describes a color's purity?

The term that describes a color's purity is hue. Hue refers to the distinct characteristic of a color that allows it to be categorized as red, blue, yellow, etc. It represents the predominant color as perceived by the human eye and is a key aspect of a color's identity. When we speak of a color having high purity, we are indicating that it is a strong, vivid representation of its hue without the influence of black, white, or gray, which can alter its intensity.

Shade, while related to hue, specifically refers to a color that has been darkened by adding black. This modification affects the hue's purity, making it less intense. Tint refers to a color that has been lightened by adding white, which also impacts the purity of the hue. Tone involves adding gray to a color, thereby reducing its brightness and altering its perceived saturation. Each of these terms relates to hue but describes different modifications rather than the characteristic of purity itself.