adjective [ only before noun ]
1.
( of buildings and places ) very carefully locked and guarded :
a high-security prison
2.
( of prisoners ) kept in a prison that is very carefully locked and guarded
adjective [ only before noun ]
1.
( of buildings and places ) very carefully locked and guarded :
a high-security prison
2.
( of prisoners ) kept in a prison that is very carefully locked and guarded
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005