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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

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."

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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.

When the Knicks walloped the Philadelphia 76ers in Game 1 of their second-round series Monday night, by the absurd score of 137-98, it extended an unprecedented three-game streak of one-sided victories.

From The Wall Street Journal • May 5, 2026

It spans 21 generations and includes more than 400 individuals, creating the foundation for an unprecedented attempt to rebuild Leonardo's genetic profile.

From Science Daily • May 4, 2026

European leaders are descending on Armenia for two unprecedented summits in a country long considered Russia's closest ally in the South Caucasus.

From BBC • May 3, 2026

In the court filing, Danco called the order "unprecedented," adding that the appeal court's decision would result in "immediate chaos" and confusion for pharmacies and patients.

From Barron's • May 1, 2026

This is Reims Cathedral in France, for which Guillaume de Machaut composed masses that were unprecedented in teir musical complexity.

From "The Story of Music" by Howard Goodall