canker
noun uk/ˈkæŋ.kər/ us/-kɚ/
(TREES)
[ C or U ] biology specialized（树木的）溃疡病，枝枯病，根瘤病
a disease that attacks the wood of trees
(ANIMALS)
[ U ] biology specialized（动物或人耳部或嘴部的）溃疡，痈，疮
a disease affecting the ears and mouth of animals and humans
(EVIL)
[ C usually singular ] formal（蔓延的）腐败;祸患;弊病
something evil that spreads through a person's mind, an organization, or a society
Poverty is a canker eating away at the heart of society. 贫穷是腐蚀社会良知的毒素。