copper-bottomed
adjective uk/ˌkɒp.əˈbɒt.əmd/ us/ˌkɑː.pɚˈbɑːt̬.əmd/
UK（计划、交易、投资等）安全可靠的，稳妥保险的
A copper-bottomed plan, deal, or investment can be trusted completely because it is safe and certain to succeed.
铜底的
having a base made of copper
a copper-bottomed saucepan 铜底的炖锅