Muted colors have tone in them.

Tone

This is very similar to “tint” and “shade,” only instead of being a hue with white or black added to it, it is a hue with only grey added to it. The grey that is added to make a “tone” must only consist of black and white, no other colors (many colors that are considered grey actually have a base that is a hue). Toned colors tend to be viewed as more sophisticated than pure hues.