mentally ill person; person with a mental disorder
Clinical or formal term; can sound blunt or stigmatizing in casual contexts. In modern sensitive usage, 精神障害者 is often preferred.
精神異常者は適切な治療を受ける権利がある。
Mentally ill persons have the right to receive appropriate treatment.
彼は精神異常者として入院していた。
He was hospitalized as a mentally ill person.
精神異常者 is a clinical, formal term for someone with a mental disorder, while 狂人 is a plainer literary word for a madman.
Compound of 精神 (mind, spirit), 異常 (abnormality), and 者 (person).