adjective
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occurring with almost no delay; immediate
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happening or completed within a moment
instantaneous death
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maths
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occurring at or associated with a particular instant
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equal to the limit of the average value of a given variable as the time interval over which the variable is considered approaches zero
instantaneous velocity
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Other Word Forms
Etymology
Origin of instantaneous
From the Medieval Latin word instantāneus, dating back to 1645–55. See instant, -an, -eous
Explanation
Something instantaneous is happening right now, without delay. In today's society, the technology we carry in our pockets means people often expect an instantaneous or immediate response to emails and text messages. Instantaneous comes from the Latin instant- meaning "being at hand." When something is instantaneous, it's right at hand when you need it. You can produce an instantaneous reply to someone or see an instantaneous change happen. If something happens very suddenly, you can describe it as instantaneous.
Vocabulary lists containing instantaneous
A Need for Speed: Synonyms for "Fast"
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"Is Survival Selfish?" Vocabulary from the argument
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Auggie & Me
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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.
Subscribers to the paid service are supposed to get almost instantaneous access to Trump's messages on the Truth Social platform -- crucial seconds ahead of the general public.
From Barron's ● Aug. 12, 2026
Asked to define the magic of their chemistry, Edwards said it was not instantaneous.
From Los Angeles Times ● Aug. 4, 2026
The thrill of these frisky flyweights is getting them to, and holding them at and around, the instantaneous limits of the tires—sawing at the wheel, pouring on the coal, pitching and catching.
From The Wall Street Journal ● Jul. 25, 2026
"The ballista spider's snare is bioengineered to store elastic energy in the silk and rapidly release it, giving it incredible instantaneous power density -- greater than any other specialized silk-based biological catapults," said Professor Narendra.
From Science Daily ● Jun. 26, 2026
He was brutally tough and on edge, with instantaneous reactions.
From "Boots on the Ground: America's War in Vietnam" by Elizabeth Partridge
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.
