Wiktionary
n. a place where persons with limited mental ability can work in a safe environment.
WordNet
n. a workshop that offers jobs to members of the physically or developmentally disabled population
Wikipedia
The term sheltered workshop refers to an organization or environment that employs people with disabilities separately from others. The term 'sheltered workshop' is considered outdated in the U.K. and the U.S., and increasingly in Australia.
Usage examples of "sheltered workshop".
Pete, Jupiter, and Ian went down through the trapdoor and crawled out into the sheltered workshop.
All the way back to the lane end, the bus driver kept on about Peter Crowther, how he lived in a hostel and worked in a sheltered workshop for nutters that the council didn't think were daft enough to be locked up, how he supposedly had some dark secret in his past and now the police thought he'd done away with Alison.