minimum security prison
noun🔊/ˌmɪnɪməm sɪˌkjʊərəti ˈprɪzn/
🔊/ˌmɪnɪməm sɪˌkjʊrəti ˈprɪzn/
(North American English) (British English open prison)
a prison in which prisoners have more freedom than in ordinary prisons 开放式监狱（对犯人的自由限制较少）