assassin       
noun [ C ] uk/əˈsæs.ɪn/ us/əˈsæs.ən/
 (通常为政治目的或钱杀死名人或重要人物的)暗杀者,行刺者,刺客
someone who kills a famous or important person, usually for political reasons or in exchange for money
  John Lennon's assassin was Mark Chapman. 刺杀约翰•列侬的人是马克•查普曼。 
 She hired an assassin to eliminate her rival. 她雇用刺客来除掉她的对手。 
 - More examples
 - The assassination could do serious damage to the fragile peace agreement that was signed last month.
 - The assassination of the Archduke Ferdinand started off the first World War.
 - President Kennedy's assassination had far-reaching repercussions.
 - The assassination was reported in all the newspapers.
 - The book describes the train of events that led up to the assassination.