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.

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instantaneous British  

/ ˌɪnstənˈteɪnɪəs, ɪnˌstæntəˈniːɪtɪ /

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

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Other Word Forms

• instantaneity noun
• instantaneously adverb
• instantaneousness noun

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.

Example Sentences

“Access to the classical studies is now instantaneous: literature, science, art, philosophy, mathematics and history.”

From Salon • Mar. 30, 2026

The entire NFL had the same instantaneous reaction: What in the name of John Madden was going on?

From The Wall Street Journal • Mar. 11, 2026

Despite instantaneous, zero-fee transactions, the explosion of exchange-traded funds, and algorithmic trading, the economic role of the U.S. public markets has been in quiet retreat.

From Barron's • Jan. 2, 2026

He recalled "a terrific flash of lightning and almost instantaneous crash of thunder, which woke quite a few people up - and probably frightened Father Christmas".

From BBC • Dec. 14, 2025

I doubt that an instant of blinding pain feels particularly instantaneous.

From "Looking for Alaska" by John Green

Related Words

• rapid
• spontaneous
• transitory