This is the 3564th most frequent Japanese word.
許せ
"許せ" (Yuruse) means "Forgive it" or "Allow it."
In this sentence, "許せない" is used to express an inability to forgive or accept something.
その失敗は許せない。
I cannot forgive that failure.
Here, "許せ" is used as a request for forgiveness in an imperative form.
私がこんなことをしてしまったことを許せ。
Please forgive me for doing such a thing.
In this sentence, "許せる" indicates the capacity or ability to forgive, urging a disposition toward forgiveness.