The adverbial expression IN UNISON /ˈjuːnəsən/ means together at the same time:
I like it so much when you play guitar in unison.
The teacher was asking questions and the children were responding in unison.
The dancers were moving in unison.
It was extraordinary: over forty voices singing in unison.
It also means in perfect agreement:
If you act in unison, it will take much less time to finish.
We said in unison that it wasn’t a good solution.
The crisis was soon over because the countries agreed to act in unison.
The EU leaders should act in unison and boycott the conference.
When people work in unison, they work together to achieve sth:
The army and the police are working in unison to catch the dangerous criminals.
For better effects these two machines should work in unison.
You will succeed only if these three factors work in unison.
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