Synonyms of instantaneous

instantaneous

adjective

ˌin(t)-stən-ˈtā-nē-əs 

as in immediate

done or occurring without any noticeable lapse in time

the thunder following the flash of lightning was nearly instantaneous

Synonyms & Similar Words

• immediate
• instant
• rapid
• split-second
• swift
• summary
• straightaway
• quick
• speedy
• prompt
• fast
• hit-and-run

Antonyms & Near Antonyms

• slow
• prolonged
• sluggish
• protracted
• tardy
• dilatory
• deferred
• delayed

Example Sentences

Recent Examples of instantaneous

And in the interior of a cell, decoherence should be basically instantaneous — quantumness shouldn’t survive long enough in such an environment to have any bearing on biology. — Elise Cutts, Quanta Magazine, 23 Sep. 2026

The standard 80% of financial advice—such as whether to invest or pay off debt, how much money to set aside for emergencies or if a purchase will interfere with a savings goal—becomes instantaneous, free and accessible to anybody with a smartphone. — Antoine Sallis, Forbes.com, 23 Sep. 2026

Lauletta and team have ambitions to achieve a rare feat in the sport — building a brand big enough to generate instantaneous recognition beyond the NASCAR bubble. — Jordan Bianchi, New York Times, 15 Sep. 2026

During the test, the laser did not appear as a long continuous light but rather an invisible almost instantaneous heat beam that hit precise points on the drone. — Eleanor Watson, CBS News, 7 Sep. 2026