cast iron
noun
mass noun
1- a hard, relatively brittle alloy of iron and carbon which can be readily cast in a mould and contains a higher proportion of carbon than steel (typically 2- 4.3 per cent)铸铁, 生铁。
1.1
- as modifier figurative firm and unchangeable〈喻〉坚定且不可改变的：
there are no cast-iron guarantees.
没有一成不变的保证。