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Synonyms

instantaneous

American  
[in-stuhn-tey-nee-uhs] / ˌɪn stənˈteɪ ni əs /

adjective

  1. occurring, done, or completed in an instant.

    an instantaneous response.

    Synonyms:
    abrupt, sudden, immediate
  2. existing at or pertaining to a particular instant.

    the instantaneous position of the rocket.


instantaneous British  
/ ˌɪnstənˈteɪnɪəs /

adjective

  1. occurring with almost no delay; immediate

  2. happening or completed within a moment

    instantaneous death

  3. maths

    1. occurring at or associated with a particular instant

    2. 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

"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 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.

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Vocabulary lists containing instantaneous

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.

See Examples For:

A camera feeding a screen in front of the pilot relies on instantaneous computer processing to get round the lack of forward vision.

From BBC ● Sep. 24, 2026

Ryan and Myers said they were fascinated with how the American news media covered the kidnapping in instantaneous fashion and in an era long before the internet.

From Los Angeles Times ● Sep. 18, 2026

Crypto firms argue that tokenization would bring a number of advantages over the current structure of the U.S. stock market, including 24/7 trading and instantaneous settlement of trades.

From The Wall Street Journal ● Aug. 18, 2026

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

But one day, she looked at a page and the word “mouse” had instantaneous meaning.

From "A Tree Grows in Brooklyn" by Betty Smith

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