sit up
phrasal verbsit up
- to be or move yourself into a sitting position, rather than lying down or leaning back
- Do you feel well enough to sit up yet?
- Sit up straight—don't slouch.
- She slowly sat up and looked around.
- to not go to bed until later than usual
- We sat up half the night, talking.
sit up (and do something)
- (informal) to start to pay careful attention to what is happening, being said, etc.
- The proposal had made his clients sit up and take notice.
sit somebody up
- to move somebody into a sitting position after they have been lying down