Where does “できぬ” come from?

できぬ (Japanese) comes from Japanese ぬ — not; has done, has happened.

Ancestry of “できぬ”, step by step

できぬ traces back through two separate lines of ancestry.

via Japanese

StepLanguageWordMeaning
1Japanesenot; has done, has happened

via Japanese できる

StepLanguageWordMeaning
1Japaneseできるto be able to do
Every word from Japanese