unheard-of

adjective

un·​heard-of ˌən-ˈhərd-ˌəv 

-ˌäv

: previously unknown

especially : unprecedented

moving at unheard-of speeds

Synonyms of unheard-of

• unprecedented
• novel
• strange
• unfamiliar
• new

Examples of unheard-of in a Sentence

houses selling at unheard-of prices

Recent Examples on the Web

To fix the problems at the factory, the company would team up with yet another unheard-of partner promising technological innovation. — Jesse Coburn, ProPublica, 12 Aug. 2026

The damage forced an almost unheard-of response from the grain trade itself. — Ingmar Rentzhog, Forbes.com, 1 Aug. 2026

Fetterman and McCormick even launched a joint fundraising committee, practically unheard-of for senators from different parties. — Burgess Everett, semafor.com, 31 July 2026

But now the Carlssons and Celebrinis can make more than that on a four or five-year deal, guaranteeing generational wealth while also setting themselves up for as-yet-unheard-of third contracts at just 26. — James Mirtle, New York Times, 30 July 2026

Word History

First Known Use

1592, in the meaning defined above

Kids Definition

unheard-of

adjective

un·​heard-of

-ˌəv, 

-ˌäv

: previously unknown : unprecedented

moving at unheard-of speeds