to prevent sb from leaving a place by locking the door :
At 9 p.m. the prisoners are locked in for the night.
to prevent sb from leaving a place by locking the door :
At 9 p.m. the prisoners are locked in for the night.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005