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• unheard-of
  unheard-of

  adjective

  that was never heard of; unknown.
• unheard of
  unheard of

  Very unusual, extraordinary, as in It's unheard of to have all one's money refunded two years after the purchase. This expression alludes to a circumstance so unusual that it has never been heard of. [Late 1500s]

unheard-of

American  

[uhn-hurd-uhv, -ov, -uhv] / ʌnˈhɜrdˌʌv, -ˌɒv, -əv /

adjective

1. that was never heard of; unknown.

   an unheard-of artist.

2. such as was never known before; unprecedented.

   an unheard-of salary.

3. shocking or outrageous.

   unheard-of conduct.

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unheard-of British  

adjective

1. previously unknown

   an unheard-of actress

2. without precedent

   an unheard-of treatment

3. highly offensive

   unheard-of behaviour

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unheard of Idioms  

1. Very unusual, extraordinary, as in It's unheard of to have all one's money refunded two years after the purchase. This expression alludes to a circumstance so unusual that it has never been heard of. [Late 1500s]

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Etymology

Origin of unheard-of

First recorded in 1585–95

Example Sentences

On Wednesday, Five Below reported nearly 23% same-store sales growth, an unheard-of number for a retailer that is now 23 years old.

From Barron's • Jun. 5, 2026

Perhaps one of Parling's greatest achievements, though, has been to bring largely unheard-of players to the fore.

From BBC • Jun. 4, 2026

He was born in Oxford, England, in 1975, and became assistant to Simon Rattle at the City of Birmingham Symphony Orchestra at the unheard-of age of 17.

From Los Angeles Times • May 26, 2026

"That's an unheard-of pace of innovation in developing complex structural alloys."

From Science Daily • Mar. 10, 2026

From twentieth, she jumped within two weeks to fifteenth, an unheard-of change in such a time.

From "The Princess Bride" by William Goldman

Related Words

• exceptional
• inconceivable
• little-known
• unbelievable
• undiscovered
• unprecedented