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

• 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

Collapsible legs fold out, creating an instantaneous cooking platform (no need to find a picnic table or flat-ish rock), and burners blast 30,000 BTUs each for searing and sizzling. —Drew Zieff, Outside Online, 8 July 2025

This reporter live-streamed it, so the fan response was instantaneous. —Ramon Ramirez, Austin American Statesman, 2 July 2025

Looking Forward Implementing continuous learning isn’t an instantaneous choice. —Prasanna Parthasarathy, Forbes.com, 2 July 2025

The entire system worked with latency down to around 10 milliseconds—the conversion of brain signals into sounds was effectively instantaneous. —ArsTechnica, 29 June 2025

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