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

By establishing secure, aggregated data-sharing APIs with the BLS, payroll processors could provide a near-instantaneous and comprehensive view of both W-2 and 1099 employment. —Jeff Gapusan, Forbes.com, 17 Sep. 2025

Its four-dimensional LiDAR even measures instantaneous velocity, allowing vehicles and robots to make safer, smarter decisions. —Ni Tao, Interesting Engineering, 15 Sep. 2025

Our testing has shown that the cellular Starlink service is sometimes instantaneous but occasionally takes several minutes to send a text message. —PC Magazine, 8 Sep. 2025

The position, size and type of injury hinted at a small but fast-moving object; a larger object would have caused more serious damage, and death probably would have been instantaneous, the study authors reported. —Mindy Weisberger, CNN Money, 29 Aug. 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