definitive
Americanadjective
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most reliable or complete, as of a text, author, criticism, study, or the like.
the definitive biography of Andrew Jackson.
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serving to define, fix, or specify definitely.
to clarify with a definitive statement.
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having its fixed and final form; providing a solution or final answer; satisfying all criteria.
the definitive treatment for an infection; a definitive answer to a dilemma.
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Biology. providing the environment in which a fully developed parasite is able to reproduce, as is provided by a definitive host.
noun
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a defining or limiting word, as an article, a demonstrative, or the like.
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Philately. a stamp that is a regular issue and is usually on sale for an extended period of time.
adjective
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serving to decide or settle finally; conclusive
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most reliable, complete, or authoritative
the definitive reading of a text
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serving to define or outline
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zoology fully developed; complete
the definitive form of a parasite
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(of postage stamps) permanently on sale
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(as noun) a definitive postage stamp
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noun
Other Word Forms
Etymology
Origin of definitive
First recorded in 1350–1400; Middle English, from Old French, from Latin dēfīnītīvus, equivalent to dēfīnīt(us) ( see definite) + -īvus adjective suffix ( see -ive)
Explanation
A definitive answer is a final one. A definitive decision by a court of law is one that will not be changed. A definitive translation is one everyone turns to as correct. Definitive means authoritative, conclusive, final. Be careful not to confuse definitive with definite. Definite means clearly defined. You can have a definite opinion that JFK could not have been assassinated by a lone gunman, but the definitive interpretation remains that of the Warren Commission Report, which held there was only one.
Vocabulary lists containing definitive
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G.1: Principles of Geography (Sources 1–14)
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Extremely Loud and Incredibly Close
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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.
“Doctors can’t make definitive declarations about legal capacity, but they can share important medical insights about your loved one’s cognitive condition, mental status and ability to understand information.”
From MarketWatch ● Aug. 20, 2026
“Specifically, the fear was that I’d go broke and not be able to handle being out of the game. But I sent the definitive email.”
From Los Angeles Times ● Aug. 19, 2026
In a statement on Friday, FSG confirmed it had entered into a "definitive agreement" for the sale of a "strategic minority investment" to 1892 Holdings.
From BBC ● Aug. 18, 2026
Although vacuum birefringence was predicted in the 1930s, Dr. Lower said scientists have yet to obtain a definitive detection.
From Science Daily ● Aug. 18, 2026
Although Frederick Griffith’s experiment was the most definitive demonstration that the gene was a chemical, other scientists were also circling the idea.
From "The Gene" by Siddhartha Mukherjee
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
