If you describe someone as ~, you mean that they watch things very carefully and seem to notice everything.
Three cannabis plants were found by ~ police officers.
ADJ
If you describe someone as ~, you mean that they watch things very carefully and seem to notice everything.
Three cannabis plants were found by ~ police officers.
ADJ
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012