(of a plan, machine, method, etc.计划、机器、方法等)very well designed and easy to use so that it cannot fail and you cannot use it wrongly使用简便的；完全可靠的；万无一失的synonyminfallible
This recipe is foolproof—it works every time.这个食谱绝对管用，每次都万无一失。🔊🔊
No system can ever be completely foolproof.任何系统都无法做到万无一失。
The system is virtually foolproof.这个系统几乎人人都会用。
We’re trying to work out a way to make the system foolproof.我们正努力想办法使这个系统简单易操作。