(~s)
An ~ is a hard and thick layer on the surface of something that has built up over a long period of time.
N-VAR
(~s)
An ~ is a hard and thick layer on the surface of something that has built up over a long period of time.
N-VAR
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012