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Synonyms

unprecedented

American  
[uhn-pres-i-den-tid] / ʌnˈprɛs ɪˌdɛn tɪd /

adjective

  1. without previous instance; never before known or experienced; unexampled or unparalleled.

    an unprecedented event.

    Synonyms:
    novel, exceptional, extraordinary, unique

unprecedented British  
/ ʌnˈprɛsɪˌdɛntɪd /

adjective

  1. having no precedent; unparalleled

"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

Other Word Forms

  • unprecedentedly adverb
  • unprecedentedness noun

Etymology

Origin of unprecedented

First recorded in 1615–25; un- 1 + precedent + -ed 2

Explanation

Something that is unprecedented is not known, experienced, or done before. If you've never gone on a family beach vacation but you're planning one now, you could refer to it as an unprecedented decision. The root of this word is precedent, a noun referring to something done or said that is used as an example to be followed in the future. In law, a precedent is a legal decision that is used as a standard in future cases. So the adjective unprecedented, meaning "having no precedent," was formed from the prefix un- "not," the noun precedent, and the suffix –ed "having."

Keep Reading on Vocabulary.com

Vocabulary lists containing unprecedented

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

But Anthropic’s Claude Mythos model shows that these rapid advancements could have unprecedented consequences if the technology falls into the wrong hands.

From MarketWatch • Apr. 18, 2026

With nuance and eagle-eyed research, he affords readers an unprecedented look at the mechanics of a musical fusion that, in many ways, we’re only just beginning to understand.

From Salon • Apr. 17, 2026

He came back to Peru four years later, received an unprecedented promotion to field marshal, and explored the country’s wild interior, searching for navigable rivers.

From The Wall Street Journal • Apr. 17, 2026

“The transaction is unprecedented in scale, resulting in the largest local broadcast television group in U.S. history.”

From Los Angeles Times • Apr. 17, 2026

They purchased guns, burglar alarms, rifles and guard dogs in unprecedented quantities.

From "Kaffir Boy: An Autobiography" by Mark Mathabane