sit down phrasal verb ( see also ↑ sit )
1 . to be in a sitting position or get into a sitting position:
It was good to be sitting down eating dinner with my family.
Sit down, Amy – you look tired.
sit yourself down
Sit yourself down and have a drink.
2 . sit somebody down to make someone sit down or help them to sit down
sit somebody down in/on
I helped her into the room and sat her down in an armchair.
3 . sit down and do something to try to solve a problem or deal with something that needs to be done, by giving it all your attention:
The three of us need to sit down and have a talk.
Sit down and work out just what you spend.