close up phrasal verb ( see also ↑ close )
1 . close something ↔ up if a shop or building closes up or is closed up, it stops being open to the public for a period of time:
The resorts are all closed up for the season.
2 . close up shop to stop doing something for a period of time or permanently:
When it rains, there is no alternative but to close up shop.
3 . if a group of people close up, they move closer together
4 . close something ↔ up if a wound closes up or if someone closes it up, the edges grow together again or are sewn together:
The scar is closing up nicely – it’ll soon be time to take the stitches out.
5 . to become narrower or to shut:
The flowers close up at night.
Occasionally the channel widened then closed up tight again.
6 . to refuse to talk to someone about something:
The moment I said I was a police officer, everyone would close up like a clam.