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 news cycle has gotten shorter in the 2020s, in large part thanks to social media and the instantaneous spread of information. —Lev Akabas, Sportico.com, 8 Jan. 2026

But by 2026, the sheer magnitude of the debt means the impact of rate hikes is instantaneous, and thus, counterproductive. —Eva Roytburg, Fortune, 5 Jan. 2026

For easy production and instantaneous delivery, the applicator needle-patches are 3D-printable, and even when used across massive leaves, provide uniform insertion. —New Atlas, 4 Jan. 2026

When humans touch something dangerously hot or sharp, sensory nerves send signals directly to the spinal cord, triggering an almost instantaneous withdrawal before the brain fully processes the pain. —Neetika Walter, Interesting Engineering, 30 Dec. 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