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

A rise in the Treasury General Account mirrors a simultaneous decline in the total stock of bank reserves as payments flow from taxpayers’ bank accounts to the Treasury.

From The Wall Street Journal • Mar. 31, 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

They showed that a single incoming stream of ions could be divided into multiple parallel streams for simultaneous analysis.

From Science Daily • Mar. 25, 2026

“We are making arrangements for a series of simultaneous exhibitions and matches for early next year. We are also considering an exhibition match where Bobby would play the entire Dutch Olympic team simultaneously.”

From "Endgame" by Frank Brady

Related Words

• concurrent