mellow

UK: /ˈmɛləʊ/ US: /ˈmɛloʊ/ ,(mel′ō)

Inflections of 'mellow' (adj):

mellower

adj comparative

mellowest

adj superlative

WordReference Random House Learner's Dictionary of American English © 2025

mel•low /ˈmɛloʊ/   adj., -er, -est, v. 
adj. 

1. sweet and full-flavored from ripeness.
2. soft and rich, as sound or colors:
   the mellow sound of the muted trumpet.
3. made gentle by age or maturity:
   became mellow after his retirement.
4. pleasantly intoxicated:
   mellow after a few drinks.
5. free from tension;
   pleasantly agreeable:
   a mellow neighborhood.

v. 

6. to (cause to) become mellow: [no object]
   The music mellowed as the band settled into a quiet mood.
   [~ + object]
   The years have mellowed her.
7. Slang Terms mellow out, [no object] to relax:
   The kids urged their parents to "mellow out.''

WordReference Random House Unabridged Dictionary of American English © 2025

mel•low  (mel′ō), adj., -er, -est, v., n. 
adj. 

1. soft, sweet, and full-flavored from ripeness, as fruit.
2. well-matured, as wines.
3. soft and rich, as sound, tones, color, or light.
4. made gentle and compassionate by age or maturity;
   softened.
5. friable or loamy, as soil.
6. mildly and pleasantly intoxicated or high.
7. pleasantly agreeable;
   free from tension, discord, etc.:
   a mellow neighborhood.
8. affably relaxed;
   easygoing;
   genial:
   a mellow teacher who is very popular with her students.

v.t., v.i. 

9. to make or become mellow.
10. Slang Terms mellow out:
    • to become detached from worry, strife, stress, etc.;
      relax:
      After final exams let's go down to the beach and mellow out.
    • to make more relaxed, agreeable, workable, etc.;
      soften or smooth:
      Chopin really mellows me out when I'm feeling tense.

n. 

11. Slang Terms a state, atmosphere, or mood of ease and gentle relaxation.

• late Middle English mel(o)we, alteration (perh. by dissimilation, in phrase meruw fruit) of Middle English meruw, Old English meru soft 1400–50

mel′low•ly, adv. 
mel′low•ness, n. 
Synonyms

• 1. See ripe. 
• 9. develop, mature, improve.

Antonyms

• 1. immature, raw, green.
• 3. harsh.

Collins Concise English Dictionary © HarperCollins Publishers::

mellow / ˈmɛləʊ/ adjective

1. (esp of fruits) full-flavoured; sweet; ripe
2. (esp of wines) well-matured
3. (esp of colours or sounds) soft or rich
4. kind-hearted, esp through maturity or old age
5. genial, as through the effects of alcohol
6. (of soil) soft and loamy

verb

1. to make or become mellow; soften; mature
2. (followed by out) to become calm and relaxed or (esp of a drug) to have a calming or relaxing effect on (someone)

Etymology: 15th Century: perhaps from Old English meru soft (as through ripeness)

ˈmellowness noun