sit back
To be built a distance away; stand away (as from a street).
Our house sits back from the road.
To relax; rest, often while others are working; take time out.
Sit back for a minute and think about what you have done.
sit by
To stay near; watch and care for.
The nurse was told to sit by the patient until he woke up.
Mother sat by her sick baby all night.
To sit and watch or rest especially while others work.
Don't just sit idly by while the other children are all busy.
sit down
take a seat
To sit on a seat or resting place.
After gym class Jim was tired and was glad to sit down and rest.
We sat down on the park bench and watched the children play.
There aren't any more chairs, but you can take a seat on the floor.
sit in
sit in on
To be a member; participate. To be a member of; participate in.
We're having a conference and we'd like you to sit in.
We want you to sit in on the meeting.
To attend but not participate. Often used with on.
Our teacher was invited to sit in on the conference.
sit on a bomb
sit on a bombshell
To be in possession of anything that is potentially disastrous or dangerous.
The finance department will be sitting on a bomb unless it finds a way to cut overhead expenses.
sit on a volcano
sitting on a powder keg
To be in a place where trouble may start or danger may come suddenly.
Bob was in that part of South America before the revolution began. He knew he was sitting on a volcano.
The policemen who patrolled the big city slum area that summer were sitting on a volcano.
sit on one's hands
To do nothing; fail or refuse to do anything.
We asked Bill for help with our project, but he sat on his hands.
sit on
To be a member of (a jury, board, commission), etc.
Mr. Brown sat on the jury at the trial.
To prevent from starting or doing something; squelch.
The teacher sat on Fred before he could get started with the long story.
The teacher sat on Joe as soon as he began showing off.