SACROILIAC Meaning of SACROILIAC in English [ ˌseɪkrəʊ'ɪlɪak , ˌsak- ]■ adjective Anatomy relating to the sacrum and the ilium. ↘denoting the rigid joint at the back of the pelvis between the sacrum and the ilium. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004