unheard-of

adjective

ˌən-ˈhərd-ˌəv How to pronounce unheard-of (audio)
Definition of unheard-ofnext
as in unprecedented
not known or experienced before houses selling at unheard-of prices

Synonyms & Similar Words

Relevance

Antonyms & Near Antonyms

Example Sentences

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.
Recent Examples of unheard-of This effort ultimately translated to a virtually unheard-of customer acquisition cost of less than one-half of one cent per new user. — Encyclopedia Britannica, 15 May 2026 The world has so many moving parts that extraordinary and even unheard-of things happen all the time. — Faye Flam, Scientific American, 7 May 2026 This is a monumental and often impossible moment for media companies, when the corporate leaders who control them have been put under unprecedented government pressure even as the rhetoric from all quarters rises to unheard-of levels. — Steven Zeitchik, HollywoodReporter, 27 Apr. 2026 In an age where most electrics are looking towards the future with unheard-of modern tech on board, the C6 sports a WWII-era girder-style front fork and a monoshock with an internal floating piston at the rear. — New Atlas, 15 Apr. 2026 See All Example Sentences for unheard-of
Recent Examples of Synonyms for unheard-of
  1. unprecedented
  2. novel
  3. strange
  4. unfamiliar
  5. new
Adjective
  • The tech giant was racing to fix weaknesses in its code that a new AI model known as Mythos was uncovering at an unprecedented clip.
    — Renee Dudley, ProPublica, 29 July 2026
  • The Incident That Changed The Conversation OpenAI disclosed that two of its models escaped a testing environment and carried out what the company itself called an unprecedented cyber incident against the AI platform Hugging Face.
    — David Chou, Forbes.com, 29 July 2026
Definition of unprecedented
Adjective
  • Anthropic says Opus 5 scored three times higher than the next-best model on ARC-AGI 3, which tests how well models solve novel problems.
    — Neetika Walter, Interesting Engineering, 24 July 2026
  • The series offers viewers insight into a setting — interwar Asia — and themes that should be novel to all but the most ardent historians.
    — David Faris, TheWeek, 23 July 2026
Definition of novel
Adjective
  • The catfish in that Vermont lake has joined a very strange club.
    — John Drake, Forbes.com, 27 July 2026
  • Of all the peculiar assignments a newspaper reporter can undertake, writing advance obituaries for local notables who are still very much alive is one of the strangest.
    — Suzanne Van Atten, AJC.com, 26 July 2026
Definition of strange
Adjective
  • Rather than introducing entirely unfamiliar concepts, companies can modernize products and experiences consumers already trust.
    — Louis Biscotti, Forbes.com, 29 July 2026
  • Espaillat, who grew up in the Dominican Republic, set out to introduce Charlotte diners to Latin Street food such as empanadas, arepas and pupusas — dishes that were largely unfamiliar here more than a decade ago.
    — Heidi Finley, Charlotte Observer, 28 July 2026
Definition of unfamiliar
Adjective
  • Lawmakers also have to decide who investigates complaints, resolves disputes and pays for any new oversight system.
    — Nora O'Neill July 28, Charlotte Observer, 28 July 2026
  • Data center facilities can be built or expanded at double or triple the pace of new electricity generations systems needed to serve them, PJM Interconnection, America’s largest grid operator, noted recently.
    — Alicia Wallace, CNN Money, 28 July 2026
Definition of new

Browse Nearby Words

unhealthy
unheard-of
unheated
See all Nearby Words

Cite this Entry

“Unheard-of.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/unheard-of. Accessed 1 Aug. 2026.

Copy Citation

More from Merriam-Webster on unheard-of

Nglish: Translation of unheard-of for Spanish Speakers

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

More from Merriam-Webster

Word of the Day

Listen to the pronunciation of spindrift

See Definitions and Examples »

Popular in Grammar & Usage

See More

7 Pairs of Commonly Confused Words

Merriam-Webster’s Great Big List of Words You Love to Hate

Is it 'nerve-racking' or 'nerve-wracking'?

Why does English have so many silent letters?

Your vs. You're: How to Use Them Correctly
See More

Popular in Wordplay

See More

Dutch Treat and French Leave: Eight Place-Based Compounds

14 Phobias You Probably Haven't Heard Of

The Longest Long Words List

The Words of the Week - Jul. 31

Even More Bird Names that Sound Like Insults (and Sometimes Are)
See More

Popular

See More

7 Pairs of Commonly Confused Words

Dutch Treat and French Leave: Eight Place-Based Compounds

14 Phobias You Probably Haven't Heard Of
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
asap street sign
Figure Out These Acronyms ASAP You don't have to be a NASA engineer to get these...
See All