Meaning : A fungal disease of woody plants that causes localized damage to the bark.
Meaning : An ulceration (especially of the lips or lining of the mouth).
Synonyms : canker sore
Meaning : A pernicious and malign influence that is hard to get rid of.
Example :
Racism is a pestilence at the heart of the nation.
According to him, I was the canker in their midst.
Synonyms : pestilence