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

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Etymology

Origin of simultaneous

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

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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

As Esteller described it, her biology showed a "fascinating duality: the simultaneous presence of signals of extreme aging and of healthy longevity."

From Science Daily ● Sep. 11, 2026

The device has a wide inner display, allowing the simultaneous use of multiple apps, and folds into a roughly passport-sized device with an outer screen.

From The Wall Street Journal ● Sep. 10, 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

Muhammad and I are at the breakfast nook checking e-mails and eating cereal when both our phones make a simultaneous beeping sound.

From "Saints and Misfits" by S.K. Ali

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Related Words

• concurrent

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