A person who is kept in prison or a hospital for people who are mentally ill. (Cambridge Dictionary)
A person who is confined in a prison, hospital, etc. (Cambridge Dictionary)
A person living in an institution such as a prison or hospital. (Cambridge Dictionary)
The inmates of a prison or mental hospital are the prisoners or patients who are living there. (Cambridge Dictionary)
Saved by Evolution: How A Prison Inmate Turned Science Into A Meaning System.
Assigning Inmates to Prison.
Convicted Inmate Law and Legal Definition.