simultaneous

adjective

si·​mul·​ta·​neous ˌsī-məl-ˈtā-nē-əs How to pronounce simultaneous (audio)
-nyəs,
 also  ˌsi-
Synonyms of simultaneousnext
1
: existing or occurring at the same time : exactly coincident
2
: satisfied by the same values of the variables
simultaneous equations
simultaneity
ˌsī-məl-tə-ˈnē-ə-tē How to pronounce simultaneous (audio) -ˈnā- How to pronounce simultaneous (audio)
 also  ˌsi-
noun
simultaneously
ˌsī-məl-ˈtā-nē-əs-lē How to pronounce simultaneous (audio)
-nyəs-
 also  ˌsi-
adverb
simultaneousness noun

Synonyms

See all Synonyms & Antonyms in Thesaurus 
Choose the Right Synonym for simultaneous

contemporary, contemporaneous, coeval, synchronous, simultaneous, coincident mean existing or occurring at the same time.

contemporary is likely to apply to people and what relates to them.

Abraham Lincoln was contemporary with Charles Darwin

contemporaneous is more often applied to events than to people.

contemporaneous accounts of the kidnapping

coeval refers usually to periods, ages, eras, eons.

two stars thought to be coeval

synchronous implies exact correspondence in time and especially in periodic intervals.

synchronous timepieces

simultaneous implies correspondence in a moment of time.

the two shots were simultaneous

coincident is applied to events and may be used in order to avoid implication of causal relationship.

the end of World War II was coincident with a great vintage year

Examples of simultaneous in a Sentence

The two gunshots were simultaneous. a simultaneous release of the movie and its soundtrack on CD
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Like those two office suites, Apple's productivity apps offer simultaneous co-editing with multiple authors, thanks to iCloud syncing. —PCMAG, 7 Nov. 2024 Many of the starry, simultaneous campaign events will be featured as part of a national livestream show Monday night airing from the seven battleground states, a senior Harris campaign official said Saturday. —Judy Kurtz, The Hill, 4 Nov. 2024 Zoom out: The Harris campaign held simultaneous Vote for Freedom rallies across the country, from Atlanta to Las Vegas and Milwaukee. —Mike D'onofrio, Axios, 5 Nov. 2024 The simultaneous arrival of TSMC and ongoing cuts on the Colorado River have pushed the city to regulate its large water users. —Austin Corona, The Arizona Republic, 4 Nov. 2024 See all Example Sentences for simultaneous 

Word History

Etymology

borrowed from Medieval Latin simultāneus "occurring at the same time," from Latin simul "in company, together, at the same time" (going back to an apocopated neuter form of similis "having characteristics in common, like") + Medieval Latin -tāneus, as in instantāneus instantaneous, Late Latin momentāneus "momentary," spontāneus "voluntary, unconstrained, spontaneous" — more at similar

Note: The Dictionary of Medieval Latin from British Sources records one occurrence of simultāneus, in the Tractatus de logica of John Wycliffe. At the entry in that dictionary the word is parsed as from simultās "occurrence at the same time" (distinct from classical Latin simultās "state of animosity") + the suffix -āneus. This analysis is possible but seems less likely. Regarding the suffix -āneus see the etymology and note at spontaneous.

First Known Use

circa 1660, in the meaning defined at sense 1

Time Traveler
The first known use of simultaneous was circa 1660

Dictionary Entries Near simultaneous

simuliid

simultaneous

simultaneous contrast

See More Nearby Entries 

Cite this Entry

“Simultaneous.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/simultaneous. Accessed 26 Nov. 2024.

Copy Citation

Share

Kids Definition

simultaneous

adjective
si·​mul·​ta·​neous ˌsī-məl-ˈtā-nē-əs How to pronounce simultaneous (audio)
-nyəs
1
: existing or occurring at the same time
2
: satisfied by the same values of the variables
simultaneous equations
simultaneously adverb
Etymology

from Latin simul "at the same time, together" and English -taneous (as in instantaneous) — related to assemble, ensemble

More from Merriam-Webster on simultaneous

Nglish: Translation of simultaneous for Spanish Speakers

Britannica English: Translation of simultaneous for Arabic Speakers

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Popular in Grammar & Usage

See All

How to Use Em Dashes (—), En Dashes (–) , and Hyphens (-)

Plural and Possessive Names: A Guide

The Difference Between 'i.e.' and 'e.g.'

Why is '-ed' sometimes pronounced at the end of a word?

What's the difference between 'fascism' and 'socialism'?
See All

Popular in Wordplay

See All

Terroir, Oenophile, & Magnum: Ten Words About Wine

8 Words for Lesser-Known Musical Instruments

10 Words from Taylor Swift Songs (Merriam's Version)

9 Superb Owl Words

15 Words That Used to Mean Something Different
See All

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Word Game Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
Missing Letter A daily crossword with a twist
little chihuahua dressing like a turkey for thanksgiving
Is That Gratitude or Attitude? A Thanksgiving Quiz Decide which words express gratitude and which gi...