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
• split-second
• straightaway

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

Whereas oral iron supplements could take upwards of six months to replenish someone’s iron levels, the results of IV iron are fairly instantaneous, says von Drygalski. —Caroline C. Boyle, USA TODAY, 19 Dec. 2024

With traditional financial systems, Wall Street just recently migrated in May 2024 to a one-day (T+1) settlement, but that is still not instantaneous. —Zain Jaffer, Forbes, 3 Dec. 2024

Don’t expect instantaneous results from LED therapy, says Matney. —Emily Orofino, Vogue, 12 Dec. 2024

Through ambient listening and real-time decision support, AI can provide these professionals instantaneous access to comprehensive information, enabling them to deliver more accurate, empathetic, and effective service. —Rajeev Ronanki, Forbes, 10 Dec. 2024

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

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