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simultaneous

[sahy-muh l-tey-nee-uh s, sim-uh l-]
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adjective
  1. existing, occurring, or operating at the same time; concurrent: simultaneous movements; simultaneous translation.

Origin of simultaneous

1650–60; < Latin simul together (see similar) + (instan)taneous
Related formssi·mul·ta·ne·ous·ly, adverbsi·mul·ta·ne·ous·ness, si·mul·ta·ne·i·ty [sahy-muh l-tuh-nee-i-tee, sim-uh l-] /ˌsaɪ məl təˈni ɪ ti, ˌsɪm əl-/, nounnon·si·mul·ta·ne·ous, adjectivenon·si·mul·ta·ne·ous·ly, adverbun·si·mul·ta·ne·ous, adjectiveun·si·mul·ta·ne·ous·ly, adverbun·si·mul·ta·ne·ous·ness, noun

Synonyms

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synchronous, coincident.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for simultaneous

simultaneous

adjective
  1. occurring, existing, or operating at the same time; concurrent
noun
  1. chess a display in which one player plays a number of opponents at once, walking from board to boardSometimes shortened to: simul
Derived Formssimultaneously, adverbsimultaneousness or simultaneity (ˌsɪməltəˈniːɪtɪ, US ˌsaɪməltəˈniːɪtɪ), noun

Word Origin

C17: formed on the model of instantaneous from Latin simul at the same time, together
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for simultaneous

adj.

1650s, from Medieval Latin simultaneus, perhaps from simultim "at the same time," extended from Latin simul "at the same time" (see similar (adj.)), or from simul with ending abstracted from Late Latin spontaneus, where the -t- is organic. Related: Simultaneously.

Online Etymology Dictionary, © 2010 Douglas Harper