(~s)
A ~ is a chemical, usually occurring naturally in your body, that makes an organ of your body do something.
N-COUNT
(~s)
A ~ is a chemical, usually occurring naturally in your body, that makes an organ of your body do something.
N-COUNT
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012