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.
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
At its brightest, it reached a luminosity of approximately 3 × 1049 erg s-1, making it one of the brightest instantaneous outbursts ever recorded in the Universe.
From Science Daily ● Jun. 26, 2026
The backlash was nearly instantaneous, and spread like wildfire across subreddits, Instagram, Facebook, even LinkedIn.
From Slate ● Jun. 15, 2026
The reaction on the part of the entire family was instantaneous; it was as though someone had thrown a match onto a pile of straw.
From "The Chosen" by Chaim Potok
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.
