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

In this modern age of technology, complete with instantaneous ways to locate talent anywhere in the world, the Duke men’s basketball coach didn’t mine social media endlessly or scour websites in recruiting the player the Charlotte Hornets selected fourth overall in the NBA Draft in June. —Roderick Boone, Charlotte Observer, 22 Oct. 2025

They’re usually found where a lot of power is needed quickly and for a limited time, like as a nearly instantaneous backup electricity for a factory or data center. —Perri Thaler, IEEE Spectrum, 22 Oct. 2025

The Babel Fish is invisible and instantaneous, not science fiction so much as fantasy. —Matteo Wong, The Atlantic, 16 Oct. 2025

The doomed vessel imploded near the Titanic wreck in the North Atlantic Ocean in 2023, resulting in the instantaneous death of all five occupants. —Michael Dorgan, FOXNews.com, 16 Oct. 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