What's the adjective for prisonlike? Here's the word you're looking for.
Included below are past participle and present participle forms for the
verbs imprison and prison which may be used as adjectives within certain contexts.
“They allow the courts to imprison people for offences which are not otherwise imprisonable.”
“Remand in custody shall generally be available only in respect of persons suspected of committing offences that are imprisonable.”
“Henceforth, every Member State will have to make it an imprisonable offence to publicly justify, deny or crudely trivialise crimes of genocide, crimes against humanity and war crimes, and I am satisfied about that.”