colour saturation

[Heatherdb1]

This makes no sense to me....
Color Saturation
Tone is related to a color’s saturation. Saturation measures the amount of gray added to dilute a pure color. For instance, a bright red is highly saturated, while a dull grayish red is unsaturated. Compare the difference between the dining rooms in Figures 1 and 2 to see the different effects of saturated and unsaturated colors.
If you dilute a pure colour with grey, would it not then be HIGHLY SATURATED? So saying a bright red is highly saturated, denotes a high amount of grey added to the red...this is bothering me...

[CelloGirl99]

So, a TONE is when a colour is diluted with gray, but SATURATION is the intensity/brightness of the colour.