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” ( similar ) + (instan)taneous

Example Sentences

Put spreads involve the simultaneous purchase and sale of put options with the same expiry but different strike prices.

From MarketWatch • Apr. 1, 2026

It felt the way I imagine those famous ’70s consciousness-raising sessions must have felt: like simultaneous creation and discovery.

From Slate • Mar. 31, 2026

French Police arrested a further 16 people in and around Paris in simultaneous raids, supported by colleagues from Europol, Eurojust and Belgian federal police.

From BBC • Mar. 30, 2026

These features allow the quantum signal and reference beam to interact in a controlled way, enabling simultaneous measurement of two conjugate quadratures.

From Science Daily • Mar. 24, 2026

I was a bit taken aback when, at eleven-thirty, simultaneous whoops broke out from all over the building.

From "Newjack: Guarding Sing Sing" by Ted Conover

Related Words

• concurrent