Also found in: Dictionary, Thesaurus, Medical, Financial, Acronyms, Encyclopedia.
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.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
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.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.