bull pen

Baseball.

Informal.

a large cell or room, usually next to the courtroom, where prisoners are temporarily held.
a large room in an office occupied by many employees.

any temporary or crowded quarters, as sleeping quarters in a lumber camp.

a pen for a bull or bulls.

Origin of bull pen

1800–10, Americanism for def 4; 1920–25 for def 1

The prisoners were finally put in the "bull-pen," and the brigade permitted to go into camp.

History of the Eighty-sixth Regiment, Illinois Volunteer Infantry, during its term of service |John R. Kinnear
Unlock him at seven in the morning, and let him come to the bull-pen.

Roads of Destiny |O. Henry
His imagination travelled on beyond the bull-pen, to the shabby dance-halls along the river.

Children of the Desert |Louis Dodge
So I said, “Lodgers are often forced into the bull-pen, too, are they not?”

Broke |Edwin A. Brown

He could not throw well enough to make his mark in that famous West ern game of bull-pen.

The Hoosier Schoolmaster |Edward Eggleston