Pertaining to coded military controls designed to prevent bombers from advancing beyond a predetermined point except on direct orders form a designated authority.

安全装置的(一种使用密码的军事控制装置，防止轰炸机在无有关单位指令之下超越预定地点)。

Guaranteed not to fail; safe from failure; fool-proof.

安全无比的；一定成功的；十分安全的。

Fail-safe point.

安全控制点。

To stop or alter an operation automatically in case of some malfunction.

(故障时)自动停止或变更操作。

To make or cause to be fail-safe.

使不失灵。