Definition of "Mellowness" :

noun: geniality, as through the effects of alcohol or marijuana

noun: a soft shade of a color

"A mellowness of light and shade not attainable in marble."

noun: the property of a sensation that is rich and pleasing

"The cheap wine had no body, no mellowness."

noun: a taste (especially of fruit) that is ripe and of full flavor

noun: a feeling of good humor and sympathy through maturity or intoxication or a relaxed state