What is the meaning of close up?

verb

• Cease to operate or cause to cease operating.
  • usage: "The owners decided to move and to close the factory"; "My business closes every night at 8 P. M."; "close up the shop"
  • synonyms: close, fold, shut down, close down
• Block passage through.
  • usage: "obstruct the path"
  • synonyms: obstruct, obturate, impede, occlude, jam, block
• Unite or bring into contact or bring together the edges of.
  • usage: "close the circuit"; "close a wound"; "close a book"; "close up an umbrella"
  • synonyms: close
• Refuse to talk or stop talking; fall silent.
  • usage: "The children shut up when their father approached"
  • synonyms: clam up, dummy up, shut up, belt up, button up, be quiet, keep mum

adverb

• Very close.
  • usage: "without my reading glasses I can hardly see things close up"; "even firing at close range he missed"
  • synonyms: at close range