simultaneous

American  

[sahy-muhl-tey-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  

/ ˌsaɪməltəˈniːɪtɪ, ˌsɪməltəˈniːɪtɪ, 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

Such an arrangement could support more simultaneous and sophisticated forms of data processing.

From Science Daily ● Aug. 17, 2026

“This raises the prospect of simultaneous disruption to both Gulf and Red Sea export routes,” Jim Reid, global head of macroeconomic research and thematic strategy at Deutsche Bank, wrote in a note on Monday.

From MarketWatch ● Jul. 27, 2026

Capital Economics warns a simultaneous closure of both waterways or damage to Saudi infrastructure could push the global economy into recession.

From The Wall Street Journal ● Jul. 17, 2026

Part of it has to do with the simultaneous leaps in quality, availability and marketing of certain shelf-stable standards: good tinned fish, squeeze-bottle olive oil, dried beans with their very own fan clubs.

From Salon ● Jul. 11, 2026

“But we forgot,” said the twins, in simultaneous despair.

From "The Secret History" by Donna Tartt

Related Words

• concurrent