Here are some possibilities, depending on the context:
Formal:
* Inmates - This is the most common and neutral term.
* Convicts - Emphasizes their legal status.
* Detainees - Used for those held in custody but not yet convicted.
Informal:
* Gang - Used for a group of prisoners, especially if they are involved in criminal activity.
* Cell block - Refers to a group of prisoners in the same housing unit.
* Population - A more general term, often used in a statistical context.
The best choice depends on the specific situation and the desired tone.