Cast-iron and Fail-safe

Cast-iron adjective - Not allowing for any exceptions or loosening of standards.

Fail-safe and cast-iron are semantically related. In some cases you can use "Fail-safe" instead an adjective phrase "Cast-iron".

Fail-safe adjective - Not likely to fail.

Cast-iron and fail-safe are semantically related. Sometimes you can use "Cast-iron" instead an adjective phrase "Fail-safe".