The property of being mellow; mellowness.

(specifically) A comfortable or relaxed mood.

(African-American Vernacular) Also main mellow: a close friend or lover.

Soften, mature, or relax something or someone.

Become softer, gentler, or more relaxed, either in terms of flavor, soil texture, or mood-altering effects from drugs.

(also figuratively, of fruit) Soft or tender by reason of ripeness; having a tender pulp.

(also figuratively, of food or drink, or its flavour) Matured and smooth, and not acidic, harsh, or sharp.

(of soil) Soft and easily penetrated or worked; not hard or rigid; loamy.

An adjective "mellow" refers to something mature, ripe, fruitful, and warm, often used in a poetic context.

An adjective "mellow" is used to describe something that is soft, delicate, calm, cheerful, easygoing, relaxed, or slightly intoxicated in a pleasant way.

(chiefly African-American Vernacular, slang) Pleasing in some way; excellent, fantastic, great.