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

The almost instantaneous virality from TikTok and the growing amount of collaborations with artists like Metro Boomin and Justin Bieber soon cemented Toliver as a mainstay in the genre. —Cerys Davies, Los Angeles Times, 30 Jan. 2026

The familiarity was instantaneous. —Peter Larsen, Oc Register, 28 Jan. 2026

In fact, Legend’s virtually instantaneous success on the main roster has earned the former WNBA star high praise from WWE officials, so much so that she’s expected to get a massive push in 2026. —Blake Oestriecher, Forbes.com, 26 Jan. 2026

This cycle elapses across thousands of years—glacially slow to us but almost instantaneous on cosmic scales. —K. R. Callaway, Scientific American, 24 Jan. 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