The Oxford Thesaurus An A-Z Dictionary of Synonyms - ulcer n.

1) sore, lesion, abscess, ulceration, canker, chancre, boil, gumboil, eruption, carbuncle, inflammation: That ulcer should be treated before it gets any worse. 2) cancer, canker, festering spot, blight, scourge, poison, disease, pestilence, curse, bane, plague: We must purge this ulcer before it corrupts the entire organization.