noun
Refers to a person serving a sentence in a correctional facility. More formal and specific than 囚人 (しゅうじん), which can also mean 'captive'.
その刑務所には約500人の受刑者が収容されている。
About 500 prisoners are housed in that prison.
受刑者の社会復帰を支援するプログラムが
Programs that support the reintegration of convicts into society are important.
服役囚 is a more colloquial or journalistic term for a prisoner serving time, whereas 受刑者 is the formal legal term.
Compound of 受刑 (じゅけい, 'undergoing punishment') + 者 (しゃ, 'person'). The term is a straightforward Sino-Japanese construction.