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unheard-of

[uhn-hurd-uhv, -ov, -uh v]
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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.

Origin of unheard-of

First recorded in 1585–95
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for unheard of

unheard-of

adjective
  1. previously unknownan unheard-of actress
  2. without precedentan unheard-of treatment
  3. highly offensiveunheard-of behaviour
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

Idioms and Phrases with 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]

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