single-person cell; isolation cell; solitary cell; solitary confinement cell
彼は独房に入れられた。
He was put in a solitary cell.
独房での生活は想像以上に厳しかった。
Life in solitary confinement was harder than imagined.
30日間の独房生活を終え、彼はようやく独房を出た。
After 30 days of solitary confinement, he finally emerged from his cell.