HEBDOMADAL Meaning of HEBDOMADAL in English [ hɛb'dɒməd(ə)l ]■ adjective formal weekly.OriginC17: from late L. ~is , from Gk hebdomas , hebdomad- 'the number seven, seven days', from hepta 'seven'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004