A kid would love to run around in a prison. There is nothing inherently prison-like about prison. The prison is because of the fact that you cannot leave that place, so that place becomes a prison.
So in an abstract sense, anything that you cannot move away from/or change, is a prison. This can apply to just about anything. Anything can become a prison, the only condition being, that you cannot move away from it. Positive or negative and other value judgments are irrelevant here, because no matter what, anything can become a prison if that is imposed. So any imposition is a prison.
Synonymous words would be: Limitation, Restriction, Attachment, Trappedness, Stuckness, Stifling, Constricting etc.
Journey to the Abstract 