“被监禁的”可以用英语表达为 "imprisoned" 或 "incarcerated"。
Imprisoned:更常用,指被关进监狱或处于监禁状态。例如:The imprisoned criminal is awaiting trial.(这名被监禁的罪犯正在等待审判。)
Incarcerated:较为正式,也指被监禁或关押,常用于法律或正式语境。例如:He has been incarcerated for ten years.(他已被监禁十年。)