Hebdomadal means weekly: hebdomadal |hebˈdämədl| adjective formal weekly (used esp. of organizations that meet weekly) : forced to eke out a meager living scribbling hebdomadal feuilletons. ORIGIN early 17th cent. (in the sense [lasting seven days] ): from late Latin hebdomadalis, from Greek hebdomas, hebdomad- ‘the number seven, seven days,’ from hepta ‘seven.’