instantaneous

adjective

in·​stan·​ta·​neous ˌin(t)-stən-ˈtā-nē-əs How to pronounce instantaneous (audio)
-nyəs
Synonyms of instantaneous
1
: done, occurring, or acting without any perceptible duration of time
death was instantaneous
2
: done without any delay being purposely introduced
took instantaneous corrective action
3
: occurring or present at a particular instant
instantaneous velocity
instantaneity
ˌin-ˌstan-tə-ˈnē-ə-tē How to pronounce instantaneous (audio)
ˌin(t)-stən-tə-ˈnē-
noun
instantaneously
ˌin(t)-stən-ˈtā-nē-əs-lē How to pronounce instantaneous (audio)
-nyəs-lē
adverb
instantaneousness noun

Synonyms of instantaneous

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Examples of instantaneous in a Sentence

We got an almost instantaneous response from the company. the thunder following the flash of lightning was nearly instantaneous
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The system effectively turns every step into an instantaneous electrochemical generator. — New Atlas, 8 Oct. 2026 Back then, subcultures had time to grow deep community roots away from an instantaneous online audience. — Sheena McKenzie, CNN Money, 8 Oct. 2026 And in the interior of a cell, decoherence should be basically instantaneous — quantumness shouldn’t survive long enough in such an environment to have any bearing on biology. — Elise Cutts, Quanta Magazine, 23 Sep. 2026 The standard 80% of financial advice—such as whether to invest or pay off debt, how much money to set aside for emergencies or if a purchase will interfere with a savings goal—becomes instantaneous, free and accessible to anybody with a smartphone. — Antoine Sallis, Forbes.com, 23 Sep. 2026 See All Example Sentences for instantaneous

Word History

Etymology

borrowed from Medieval Latin instantāneus, from instant-, instans "moment, point of time," + Latin -āneus, suffix forming adjectives from temporal adverbs — more at instant entry 1

Note: Regarding the suffix -āneus see the etymology and note at spontaneous.

First Known Use

1651, in the meaning defined at sense 1

Time Traveler
The first known use of instantaneous was in 1651

Rhymes for instantaneous

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Browse Nearby Words

instantaneity
instantaneous
instantaneous exposure
See all Nearby Words

Cite this Entry

“Instantaneous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/instantaneous. Accessed 14 Oct. 2026.

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Kids Definition

instantaneous

adjective
in·​stan·​ta·​neous ˌin(t)-stən-ˈtā-nē-əs How to pronounce instantaneous (audio)
-nyəs
1
: happening in an instant
2
: done without delay
instantaneously adverb
instantaneousness noun
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