instantaneous

adjective

in·​stan·​ta·​neous ˌin(t)-stən-ˈtā-nē-əs 

-nyəs

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 

ˌin(t)-stən-tə-ˈnē-

noun

instantaneously

ˌin(t)-stən-ˈtā-nē-əs-lē 

-nyəs-lē

adverb

instantaneousness noun

Synonyms of instantaneous

• immediate
• instant

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

While the near synchronicity of the worldwide foram flips might seem puzzling, Darling and Ujiié pointed out that what appears instantaneous in the fossil record might unfold over 1,000 years or more in real time. — Quanta Magazine, 11 Sep. 2026

During the test, the laser did not appear as a long continuous light but rather an invisible almost instantaneous heat beam that hit precise points on the drone. — Eleanor Watson, CBS News, 7 Sep. 2026

The impression from their new arrival was instantaneous, and helped Everton to a draw that feels worth far more than a solitary point against a middling United side. — Patrick Boyland, New York Times, 6 Sep. 2026

But fantasy sports, an almost quaint precursor to the instantaneous forms of gambling proliferating now, remains hugely prevalent. — Hannah Keyser, CNN Money, 3 Sep. 2026

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

Rhymes for instantaneous

• aeneas

Kids Definition

instantaneous

adjective

in·​stan·​ta·​neous ˌin(t)-stən-ˈtā-nē-əs 

-nyəs

1

: happening in an instant

2

: done without delay

instantaneously adverb

instantaneousness noun