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

Derived Forms

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

As Coleman notes, "Simultaneous space- and ground-based observations of microlensing events could be applied in the planning of future exploratory missions and could lead to a better understanding of how planets form across the Galaxy."

From Science Daily • Jan. 4, 2026

Simultaneous meetings of three of the top four are even more unusual, and it’s downright rare for all four banks’ meetings to overlap.

From Barron's • Oct. 28, 2025

Simultaneous wage increases for childcare workers in the state had a similar effect, with just 16% of childcare providers living in poverty compared to 27.4% in 2020.

From Salon • Jun. 3, 2025

Simultaneous exhibitions opened on Friday at 12 institutions, putting more than half of the population within an hour of one of the masterpieces.

From BBC • May 10, 2024

Simultaneous and contradictory information declared him victorious in Villanueva, defeated in Guacamayal, devoured by Motilón Indians, dead in a village in the swamp, and up in arms again in Urumita.

From "One Hundred Years of Solitude" by Gabriel Garcia Marquez

Related Words

• concurrent