柯林斯詞典mortal sin (mortal sins) 1. N-VAR In the Roman Catholic Church, a mortal sin is an extremely serious sin. Catholics believe the person who has committed it will be punished after death unless they are forgiven by the Church. (天主教的)不可饒恕的大罪 返回 mortal sin劍橋詞典in the Roman Catholic religion , an action that is so bad that you will be punished for ever after your death if you do not ask God to forgive you (天主教中的)彌天大罪 返回 mortal sin