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definitions

mellow

[mel-oh]
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adjective, mel·low·er, mel·low·est.
  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.
verb (used with or without object)
  1. to make or become mellow.
noun
  1. Slang. a state, atmosphere, or mood of ease and gentle relaxation.
Verb Phrases
  1. mellow out, Slang.
    1. to become detached from worry, strife, stress, etc.; relax: After final exams let's go down to the beach and mellow out.
    2. to make more relaxed, agreeable, workable, etc.; soften or smooth: Chopin really mellows me out when I'm feeling tense.

Origin of mellow

1400–50; late Middle English mel(o)we, alteration (perhaps by dissimilation, in phrase meruw fruit) of Middle English meruw, Old English meru soft
Related formsmel·low·ly, adverbmel·low·ness, nouno·ver·mel·low, adjectiveo·ver·mel·low·ly, adverbo·ver·mel·low·ness, nounun·mel·low, adjectiveun·mel·lowed, adjective

Synonyms for mellow

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

Antonyms for mellow

1. immature, raw, green. 3. harsh.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for mellow out

unwind, recline, slow, slacken, ebb, wane, dwindle, recede, taper, subside, decrease, diminish, dull, quit, acquiesce, relax, soften, capitulate, comply, decline
British Dictionary definitions for mellow out

mellow

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. (foll by out) to become calm and relaxed or (esp of a drug) to have a calming or relaxing effect on (someone)
Derived Formsmellowly, adverbmellowness, noun

Word Origin for mellow

C15: perhaps from Old English meru soft (as through ripeness)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Word Origin and History for mellow out

mellow

adj.

mid-15c., melwe "soft, sweet, juicy" (of ripe fruit), perhaps related to melowe, variant of mele "ground grain" (see meal (2)), influenced by Middle English merow "soft, tender," from Old English mearu. Meaning "slightly drunk" is from 1680s. Mellow yellow "banana peel smoked in an effort to get high" is from 1967. Related: Mellowly; mellowness.

mellow

v.

1570s, from mellow (adj.). Related: Mellowed; mellowing.

Online Etymology Dictionary, © 2010 Douglas Harper
Idioms and Phrases with mellow out

mellow out

Become genial or pleasant, calm down, relax, as in The teacher mellowed out when they explained what had happened. This expression uses mellow in the sense of “ripening,” with the connotation of softness and sweetness. [Slang; late 1900s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.