(n.) The state or quality of being irrevocable; irrevocableness.

certainty fate fatefulness force majeure indefeasibility ineluctability inescapableness inevasibleness inevitability inevitable accident inevitableness inexorability inflexibility irrevocability necessity predetermination relentlessness sureness unavoidable casualty unavoidableness uncontrollability undeflectability unpreventability unyieldingness vis major