Fetching details from the dictionary...
Rarely used in modern Japanese. Common alternatives: ない (not exist) / 亡くなる (to pass away).
dead
祖父そふはもう亡くなくなっなった。
My grandfather has already passed away.
父ちちが亡かっなかったのは十じゅう年ねん前まえのことだ。
It was ten years ago that my father passed away.
祖父そふはまだ亡くなくないと皆みなが信じしんじていた。
Everyone believed that our grandfather was not yet dead.