Translation guide
The English word "unthinkable" describes something so shocking, immoral, or impossible that it cannot be imagined or considered. In Japanese, there is no single perfect equivalent. Instead, you express the idea using words and phrases that convey impossibility, moral outrage, or something beyond imagination, depending on the context.
Expressing that an action or idea is so wrong that it should not even be considered.
Literally 'cannot be thought of'. This is the most direct and common way to say something is unthinkable in the sense of being unacceptable or unimaginable. It can be used in both casual and formal contexts.
It's unthinkable that he would do such a thing.
Hurting someone is an unthinkable act.
Means 'impossible' or 'unbelievable'. Often used in spoken Japanese to express that something is out of the question or completely unacceptable. Stronger and more colloquial than 考えられない.
Means 'unforgivable' or 'not permitted'. Use this when the unthinkable act is a moral transgression that cannot be tolerated.
Such cruelty is unthinkable (unforgivable).
Literally 'beyond imagination'. Used for something so terrible or extreme that it defies imagination. Often found in written or formal contexts.
Expressing that something is so unlikely or extraordinary that it cannot be imagined as real.
Means 'cannot imagine'. A straightforward way to say something is beyond imagination, often used for both positive and negative situations.
The vastness of space is unthinkable.
It was unthinkable that he would fail.
Means 'unbelievable'. Commonly used in everyday speech to express shock or disbelief. It can overlap with 'unthinkable' when something is hard to accept as true.
Unthinkable! Did you really do it?
Expressing that an option is completely ruled out or impossible under the circumstances.
Means 'out of the question' or 'not worth discussing'. Strongly dismisses an idea as unthinkable or absurd. Common in debates or when rejecting proposals.
A price increase is unthinkable (out of the question).
As above, this can also mean 'impossible' in a logical sense. Use it to flatly deny a possibility.
Similar to 論外, meaning 'out of the question'. Slightly more formal and less common in casual speech.
That proposal is unthinkable.
There is no single Japanese adjective that directly translates 'unthinkable' in all contexts. Using a dictionary form like 考えられない is often the safest, but always consider the nuance: moral outrage, impossibility, or surprise.
考えられない is more about what you cannot mentally conceive or accept, while ありえない is a stronger denial of possibility. ありえない is more colloquial and can sound dismissive.
そんなのありえないよ！
That's unthinkable! / No way!
It's unthinkable that he would be late.
The devastation of the accident was unthinkable.
Means 'unexpected' or 'beyond what one could think'. It emphasizes that something never crossed your mind. Often used for surprising events.
The result was unthinkable.
彼が辞めるなんてありえない選択だ。
Him quitting is an unthinkable option.