ecclesiologyEnglishOxford Dictionary of Englishecclesiology /ɪˌkliːziˈɒlədʒi / ▸ noun [mass noun] 1 theology as applied to the nature and structure of the Christian Church. 2 the study of churches, especially church building and decoration. – DERIVATIVES ecclesiological /ɪˌkliːzɪəˈlɒdʒɪk(ə)l/ adjective ecclesiologist noun– ORIGIN mid 19th century: from Greek ekklēsia ‘assembly, church’ + -logy.