Concise Bible Dictionary:
The word of those who err from the truth eats like a “gangrene” which consumes the flesh. Such teaching saps the vitals of Christianity (2 Tim. 2:17).
Gangrene of the Lung
Strong’s Dictionary of Greek Words:
Transliteration:
gaggraina
Meaning:
from γραίνω (to gnaw); an ulcer ("gangrene")