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

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

Lauletta and team have ambitions to achieve a rare feat in the sport — building a brand big enough to generate instantaneous recognition beyond the NASCAR bubble. — Jordan Bianchi, New York Times, 15 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

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