Translation guide
Describes a system, plan, or device designed to revert to a safe condition in the event of failure, or a precautionary measure to prevent disaster.
The core engineering meaning: a mechanism that, if it fails, does so in a way that causes no harm (e.g., a brake that engages when power is lost).
The direct loanword, widely used in technical and engineering contexts. It is the most common way to express the concept in Japanese.
This system has a fail-safe design.
A more literal Japanese compound meaning 'safe at time of failure'. Used in formal specifications and patents.
A device equipped with a fail-safe function.
A descriptive phrase meaning 'to operate on the safe side'. Used in explanations rather than as a fixed term.
It is designed to operate on the safe side in case of abnormality.
An action or arrangement taken to ensure safety or prevent failure, often in non-engineering contexts like business or daily life.
Literally 'safety measure'. A natural, general term for any precaution taken to avoid risk.
We took a fail-safe measure just in case.
Means 'preventive measure'. Emphasizes stopping a problem before it happens, similar to a fail-safe in planning.
Literally 'to take out insurance'. A figurative expression meaning to have a backup or safety net.
A formal phrase meaning 'a measure taken just in case'. Suitable for official documents.
フェイルセーフ is strictly an engineering term for automatic safe failure. 安全策 is a broader 'safety measure' that can be used in any context, including business or daily life. Use フェイルセーフ when describing a technical design; otherwise, 安全策 or 予防策 is more natural.
This brake is fail-safe.
The project needs a fail-safe.
Do not translate 'fail-safe' literally as 失敗安全 (しっぱいあんぜん) or 失敗しても安全 (しっぱいしてもあんぜん). These are not natural Japanese and will not be understood. Stick to the loanword フェイルセーフ or the contextual alternatives above.
We prepared a fail-safe to avoid trouble.
Let's think of another plan as a fail-safe, just in case.
The loanword 'backup'. Often used for fail-safe systems or alternative plans in IT and business.
Build a fail-safe into the system.
As a fail-safe, we perform a double check.