(~s)
An ~ is a device that is connected to a cylinder of oxygen by means of a tube. It is placed over the nose and mouth of someone who is having difficulty in breathing in order to help them breath more easily.
N-COUNT
(~s)
An ~ is a device that is connected to a cylinder of oxygen by means of a tube. It is placed over the nose and mouth of someone who is having difficulty in breathing in order to help them breath more easily.
N-COUNT
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012