We use 'insist' when someone says something very strongly. They believe it is true or very important. It shows strong feeling.
She insists on finishing her homework.
He insists that it is the right choice.
To 'insist' means to keep asking or saying that something must happen. People do not stop even if others disagree.
I insist on eating healthy food every day.
They insist that we come to the meeting.
When someone 'insists' in this way, they tell you strongly to do something. They want you to listen to their advice or idea.
I insist you try the new cake; it is very good.
She insists that you call her if you are late.
'Insist' in legal talk means to strongly demand or say that something is true or must happen. It often happens in serious talks or court.
The lawyer insists on the contract terms being clear.
The witness insists that the events happened that way.
When someone 'insists' about a fact, they say strongly that it is true, even if others do not believe them.
He insists that he was at home all day.
They insist they did nothing wrong.