EXOSTOSIS Meaning of EXOSTOSIS in English [ ˌɛksɒs'təʊsɪs ]■ noun ( plural exostoses -si:z ) Medicine a benign outgrowth of cartilaginous tissue on a bone.OriginC16: from Gk, from ex- 'out' + osteon 'bone'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004