Simultaneously means at the same time, at the same moment. It describes two actions or events that happen at once. The word is formal: it fits essays, reports and the news, while in conversation people usually say at the same time.
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verb + simultaneously (happen, run, work simultaneously); be + simultaneously + past participle (was released simultaneously); simultaneously + verb
- The film will be released simultaneously in cinemas and on the streaming service.
- Our teams in Seoul and London worked on the report simultaneously, so it was ready by Monday.
- Two alarms went off simultaneously, and nobody knew which one to check first.
What changed
First versionSocial media helps people stay in touch. Simultaneously, it can make them feel lonely.
RevisionSocial media helps people stay in touch. At the same time, it can make them feel lonely.
At the same time has two uses: “at the same moment” and “however, on the other hand”. Simultaneously only has the first. The second sentence isn't about timing but about a downside of social media set against an advantage, so Simultaneously was replaced with At the same time.
In its literal sense, at the same time also means “at the same moment”, and it's the usual choice in conversation: We both started talking at the same time. Simultaneously sounds more formal and is more common in texts about technology, events and processes: The two programmes run simultaneously on one computer.
Your turn
The two films were released ___ on 5 May, so critics reviewed them in the same week.
Show the answer
simultaneously — You need a word that describes the verb itself: the films came out at the same time, on the same day. That's simultaneously. Meanwhile doesn't work like that: it links two sentences and means “during that time”, while something else is happening.
Describe a time at work or in your studies when you had to do two things at once. Name both tasks and say how it turned out.
Last Friday I had to answer client emails and prepare a presentation simultaneously, so I made several typos in the slides.
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