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

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

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

Data compiled by AFP showed prolonged blackouts and record generation shortfalls in recent days -- 65 percent of Cuban territory endured simultaneous blackouts on Tuesday.

From Barron's • May 14, 2026

“Trump arguably faces a tight-wire act of simultaneous diplomacy and negotiation more complicated than any he’s yet seen in either of his presidencies.”

From The Wall Street Journal • May 10, 2026

And simultaneous to Villa's triumph, Crystal Palace followed up a 3-1 victory against Shakhtar Donetsk seven days ago with a 2-1 win against the Ukrainian side at Selhurst Park in the second leg.

From BBC • May 7, 2026

The artificial-intelligence boom’s forecasted energy needs exceed supply, according to most estimates, unless there is a simultaneous investment boom in power generation.

From MarketWatch • Apr. 27, 2026

Though I embraced my simultaneous roles as athlete and activist, there were times at the games when I craved time outside of the spotlight.

From "Proud" by Ibtihaj Muhammad

Related Words

• concurrent