canker

Meanings

Noun

• a fungal disease of woody plants that causes localized damage to the bark
• an ulceration (especially of the lips or lining of the mouth)
• a pernicious and malign influence that is hard to get rid of
  • "according to him, I was the canker in their midst"

Verb

• become infected with a canker
• infect with a canker

Synonyms

canker sore, pestilence