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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.

From the vantage point of 2026, as we endure an unprecedented degree of barbarism at every level of society, we see how disastrous his prescriptions were.

From Salon • Apr. 19, 2026

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

The Lebanese government has taken unprecedented steps to counter the influence of Hezbollah and Iran.

From The Wall Street Journal • Apr. 17, 2026

He said the approach addresses “complex challenges created by these unprecedented drought conditions which require immediate action.”

From Los Angeles Times • Apr. 17, 2026

Before 1919 was over, in an unprecedented demonstration of labor unrest, there would be thirty-six hundred work stoppages involving four million workers or one-fifth of the nation’s labor force.

From "1919 The Year That Changed America" by Martin W. Sandler