pen up

pen up

To imprison or confine someone or an animal inside of a pen or a similarly small, restricted space. We pen these convicts up with other criminals for years at a time, and you expect them all to become reformed citizens as a result? The man had penned up dozens of wild animals in a disused corner of his company's warehouse.
See also: pen, up
Farlex Dictionary of Idioms.

pen (someone or an animal) up

to confine someone to a confined space or an animal to a pen. He said he didn't want them to pen him up in an office all day. They penned up the dog during the day.
See also: pen, up
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • pen in
  • in ink
  • pen and ink
  • never dip your pen into the company's ink
  • intern
  • intern in
  • intern in (something)
  • corral
  • corral (someone or something)
  • chase in some place