noun
Formal term for a person currently held in a prison or detention facility. Used in legal and administrative contexts.
在監者の人権が守られるべきだ。
The human rights of prisoners should be protected.
受刑者 refers to a convicted prisoner serving a sentence, whereas 在監者 can include those awaiting trial or detained for other reasons.
Compound of 在監 (ざいかん, 'being in prison') + 者 (しゃ, 'person'). The term is straightforwardly derived from its components.