Someone who is ~ is much less advanced mentally than most people of their age. (OLD-FASHIONED)
...a special school for mentally ~ children.
ADJ
Someone who is ~ is much less advanced mentally than most people of their age. (OLD-FASHIONED)
...a special school for mentally ~ children.
ADJ
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012