ulcerEnglishOxford English Thesaurusulcer noun most leg ulcers will heal spontaneously: sore, ulceration, open sore, abscess, boil, carbuncle, pustule, blister, cyst, gumboil, wen; North American canker sore; technical aphtha, chancre, furuncle, vesication, noma; archaic gathering, fester, impostume.ulcer Oxford Dictionary of English