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

With the craft's communications failing within the first two hours, the submersible imploded upon descent, resulting in their instantaneous deaths. — Dan Snierson, Entertainment Weekly, 16 June 2026

Speaking of which, when news broke Friday that much of the team’s equipment had been stolen, there was a nearly instantaneous social media ridiculing of the city. — Kansas City Star, 15 June 2026

Even with faster platforms, vaccine development is still not instantaneous. — Paul Adepoju, Scientific American, 14 June 2026

Some of these events are planned and attended by young adults, most of whom hardly remember a world before instantaneous digital communication. — Audrey Pachuta, Chicago Tribune, 12 June 2026