General confinement:
* Confinement: This is the most direct noun form, meaning the state of being confined.
* Restriction: This emphasizes the limitation of movement or freedom.
* Imprisonment: This specifically refers to being locked up in a prison.
Specific types of confinement:
* Enclosure: A physical space that confines something.
* Captivity: Being held against one's will.
* Sequestration: Being isolated from the outside world.
The best noun form to use depends on the specific situation and the nuance you want to convey.