parasite
noun [ C ] uk/ˈpær.ə.saɪt/ us/ˈper.ə.saɪt/
寄生生物；寄生动物；寄生植物
an animal or plant that lives on or in another animal or plant of a different type and feeds from it
The older drugs didn't deal effectively with the malaria parasite. 以前的药物不能有效对付引起疟疾的寄生虫。
disapproving靠他人为生者，寄生虫
a person who is lazy and lives by other people working, giving them money, etc.
Financial speculators are parasites on the national economy. 金融投机者是国民经济的寄生虫。