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

Whipped up and given a sheen of analytic legitimacy by the Maven, military officials did not do their due diligence in the midst of hundreds of similar, simultaneous strikes.

From Salon ● Aug. 12, 2026

McDonald's reported slower sales growth in the US market in the second quarter as executives blamed too many simultaneous promotional offers, including a World Cup campaign that disappointed.

From Barron's ● Aug. 4, 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

Figure 1.47: When multiple simultaneous rhythms are written on the same staff, rests may be used to clarify individual rhythms, even if another rhythm contains notes at that point.

From "Understanding Basic Music Theory" by Catherine Schmidt-Jones and Russel Jones

Related Words

• concurrent