multi-person cell; shared cell
Used in prison contexts for a cell housing multiple inmates together.
In this prison, minor offenders are often placed in shared cells.
独房 is a cell for one prisoner in isolation, while 雑居房 is a shared cell holding multiple prisoners together.
Compound of 雑居 (ざっきょ, 'living together') and 房 (ぼう, 'cell, room').