1A medical suffix meaning inflammation (equivalent to English -itis); used in compounds to indicate an inflammatory disease (e.g. pneumonia: 肺炎).
彼は肺炎（はいえん）で入院した。
He was hospitalized with pneumonia.
扁桃腺炎（へんとうせんえん）は喉の痛みや発熱を伴うことが多い。
Tonsillitis often comes with a sore throat and fever.
関節炎（かんせつえん）の痛みで朝起きるのがつらい。
Waking up because of arthritis pain is painful.