simultaneous

American  

[sahy-muhl-tay-nee-uhs, sim-uhl-] / ˌsaɪ məlˈteɪ ni əs, ˌsɪm əl- /

adjective

1. existing, occurring, or operating at the same time; concurrent: simultaneous translation.

   simultaneous movements;

   simultaneous translation.

   Synonyms:

   coincident, synchronous

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simultaneous British  

/ ˌsaɪməlˈteɪnɪəs, ˌsɪməlˈteɪnɪəs /

adjective

1. occurring, existing, or operating at the same time; concurrent

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noun

1. Sometimes shortened to: simul. chess a display in which one player plays a number of opponents at once, walking from board to board

Other Word Forms

• simultaneity
  noun
• simultaneousness
  noun
• unsimultaneousness
  noun
• nonsimultaneous
  adjective
• unsimultaneous
  adjective
• simultaneously
  adverb

Etymology

Origin of simultaneous

First recorded in 1650–60; from Latin simul “together” ( see similar) + (instan)taneous

Explanation

The adjective simultaneous describes something that is done at the same time as something else. "The teachers all assigned simultaneous projects to the students that week. The kids were grumbling and sleep-deprived due to the grind." The Latin root of simultaneous is simul, which also means "at the same time." One way to remember this word is to think of simulcast programs that are simultaneously available through different television networks, radio stations or Web sites — so you can catch that concert on TV while your friend is listening to it on his car radio.

Example Sentences

See Examples For:

simultaneous

So the idea was having Bernadette really be the mastermind of John’s upbringing as a way to provide a simultaneous salve for her husband’s shame about being afraid about losing out on the opportunity.

From Los Angeles Times ● Oct. 5, 2026

They discuss the exponential pace of AI development, what the big companies are or are not doing to protect humans from apocalypse, and the simultaneous governmental and industry cooperation that could help manage risks.

From Slate ● Sep. 10, 2026

Hundreds of Star Trek fans are set to gather at London's Science Museum to try and set the Guinness World Record for the largest simultaneous Vulcan salute.

From BBC ● Sep. 1, 2026

Bailey said banks and other financial institutions should prepare for “more severe scenarios involving simultaneous disruption across multiple firms or shared technology dependencies.”

From The Wall Street Journal ● Aug. 31, 2026

A national group called the People-to-People Committee was attempting to raise funds for the team, and the executive director asked Bobby if he’d give a simultaneous exhibition to publicize the team’s plight.

From "Endgame" by Frank Brady

Related Words

• concurrent