You use ~ in front of an adjective describing a positive quality in order to emphasize the quality expressed by that adjective.
His books on diplomatic history were ~ readable...
= highly
ADV: ADV adj/-ed emphasis
You use ~ in front of an adjective describing a positive quality in order to emphasize the quality expressed by that adjective.
His books on diplomatic history were ~ readable...
= highly
ADV: ADV adj/-ed emphasis
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012