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

While greenhouse gasses released into the atmosphere can linger for years, once air pollution is reduced the health benefits are nearly instantaneous. —Simmone Shah, Time, 22 Aug. 2025

Actionable insights that should be instantaneous can take hours, or days, to assemble. —Arunabh Dastidar, Forbes.com, 18 Aug. 2025

What would The Canterbury Tales be if the pilgrimage from the Tabard Inn to the Shrine of Thomas Becket were instantaneous? —Emil Steiner, Forbes.com, 14 Aug. 2025

For one thing, events such as the Locarno fest’s Aug. 8 presentation of its Leopard Club career achievement award to Emma Thompson, draw far more coverage and generate more buzz in the age of instantaneous online media. —Cynthia Littleton, Variety, 11 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