What term refers to a concentrated color used to reduce red or gold highlights?

The term that refers to a concentrated color used specifically to reduce unwanted red or gold highlights in hair is "drabber." Drabbers are formulated colors that counteract warm tones and help achieve a cooler or more neutral hair color. They are typically mixed with hair color formulations or used directly during the coloring process to balance out warmth.

In the context of hair coloring, drabbers act similarly to color theory principles, where colors opposite on the color wheel neutralize each other. For example, green drabbers can neutralize red tones, while violet drabbers can help reduce gold or yellow hues. This makes them invaluable tools for colorists aiming for more precise and desirable results in hair color.