finality

1. N-UNCOUNT Finality is the quality of being final and impossible to change. If you say something with finality, you say it in a way that shows that you have made up your mind about something and do not want to discuss it further. 终结性; 定局[正式] [oft N 'of' n]

Young children have difficulty grasping the finality of death. 小孩子很难理解死亡的终局性。