noun
indeterminate sentence
A legal term for a prison sentence whose length is not fixed at the time of sentencing, but may be adjusted based on behavior or other factors.
不定期刑は、受刑者の更生状況によって刑期が変わる制度です。
An indeterminate sentence is a system where the prison term changes depending on the inmate's rehabilitation progress.
Compound of 不 (fu, 'not') + 定期 (teiki, 'fixed period') + 刑 (kei, 'penalty'). The term is a direct translation of the Western legal concept of indeterminate sentencing.