unheard-of

adjective

un·​heard-of ˌən-ˈhərd-ˌəv How to pronounce unheard-of (audio)
-ˌäv
Synonyms of unheard-ofnext
: previously unknown
especially : unprecedented
moving at unheard-of speeds

Synonyms of unheard-of

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Examples of unheard-of in a Sentence

houses selling at unheard-of prices
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The Financial Times reported last month that Anthropic’s and OpenAI’s IPO advisers were lobbying credit-rating agencies for blue-chip status, which would be almost unheard-of for companies as unprofitable as both AI labs are. — Ellen Dimauro, semafor.com, 13 Oct. 2026 The museum’s floor plan, especially its curved walls, presented previously unheard-of challenges for exhibiting artworks. — Wendy S. Walters, Architectural Digest, 12 Oct. 2026 An unheard-of benefit for this group of patients with this terrible disease. — Bryan C. Donohue, Baltimore Sun, 1 Sep. 2026 The band features an almost unheard-of 11 musicians, all among Ireland’s best in their musical specialties. — Dan Kelly august 30, Kansas City Star, 30 Aug. 2026 See All Example Sentences for unheard-of

Word History

First Known Use

1592, in the meaning defined above

Time Traveler
The first known use of unheard-of was in 1592

Browse Nearby Words

unheard
unheard-of
unhearing
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Cite this Entry

“Unheard-of.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unheard-of. Accessed 21 Oct. 2026.

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Kids Definition

unheard-of

adjective
un·​heard-of
-ˌəv, 
-ˌäv
: previously unknown : unprecedented
moving at unheard-of speeds
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