noun
ulcer
Medical term for an open sore on the skin or a mucous membrane, such as a stomach ulcer.
胃潰瘍の治療には時間がかかることがあります。
Treatment for a stomach ulcer can take time.
口内炎がひどくなると潰瘍になることもある。
A mouth sore can sometimes develop into an ulcer.
The kanji 潰 means 'to crush' or 'to fester', and 瘍 means 'sore' or 'boil'. Together they form the medical term for ulcer. The reading かいよう is the on'yomi for both characters.