MYOSITIS Meaning of MYOSITIS in English [ ˌmʌɪə(ʊ)'sʌɪtɪs ]■ noun Medicine inflammation and degeneration of muscle tissue.OriginC19: formed irregularly from Gk mus , mu- 'muscle' + -itis . Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004