sit up

sit up  {v.}
1. To move into a sitting position.
Joe sat up when he heard the knock on his bedroom door.
2. To stay awake instead of going to bed.
Mrs. Jones will sit up until both of her daughters get home from the dance.
We sat up until two A.M. hoping for news from Alaska.
3.  {informal}
To be surprised.
Janice really sat up when I told her the gossip about Tom.
Categories: informal verb

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