simultaneously

simultaneously — adverb

1. when something happens or is done at the same moment as one or more other things

1.adverbB2
Definition

when something happens or is done at the same moment as one or more other things, so that none of them starts earlier or later — for example, two phones ringing at once, or two runners crossing the finish line in the same split second.

Example

Naoko was talking on the phone and simultaneously checking her email on the laptop.

position between coordinated verb phrases

The two presenters started their talks simultaneously at exactly ten o'clock.

end position after verb phrase

Common collocations
  • happen simultaneously
  • occur simultaneously
  • arrive simultaneously
  • speak simultaneously
  • press...simultaneously
  • buzz simultaneously
  • ring simultaneously
  • launch simultaneously
Synonyms
  • concurrently

    more formal and technical, common in legal or computing contexts

  • at the same time

    the everyday spoken equivalent; less formal than simultaneously

  • in unison

    specifically of coordinated action by a group, often with the same intent

  • together

    broader — can mean 'with each other' rather than 'at the same moment'

Antonyms

Grammar Patterns

simultaneously + [verb]

[verb phrase] + simultaneously

Simultaneously, + [clause]

Usage Note

Often used with verbs of occurrence, movement, or communication — for example, happen, occur, arrive, speak, start, press, buzz, or ring. The word can move freely within a clause without changing the core meaning: before the main verb (simultaneously checked), after the verb phrase (opened simultaneously), or at the start of the clause (Simultaneously, the audience rose).

Common Mistakes

The two events occurred simultaneously at the same time.
The two events occurred simultaneously.' or 'The two events occurred at the same time.
'simultaneously' and 'at the same time' mean the same thing; using both together is redundant.

Word family

Synonym discussion

Sense: adverb/1

Simultaneously is the most precise word for 'at exactly the same moment' and works in both everyday and formal English. Concurrently is more formal and often used in legal, academic, or technical contexts — two prison sentences can run concurrently, but you would not say two friends arrived concurrently. At the same time is the ordinary spoken alternative ('We both spoke at the same time') and is less precise: it can also mean 'despite that' ('I like the design; at the same time, it is too expensive'). In tandem adds the idea of two things working together in coordination, not just at the same moment — for example, two departments working in tandem on a project. If you mean pure simultaneity without collaboration, use simultaneously.

simultaneously ↗concurrentlyat the same timein tandem

Etymology

LatinEnglish

The word comes from Latin 'simul' (meaning 'together, at the same time'), through Medieval Latin 'simultaneus', which was adopted into English as the adjective 'simultaneous' in the 1600s. The adverb 'simultaneously' was formed by adding the common '-ly' suffix to that adjective.