subdural UK /sʌbˈdjʊə.ɹəl/US /ˌsʌbˈd(j)ʊɹ.əl/adjective 1noun 1forms 1 adjective1 •Located beneath the dura mater and above the arachnoid mater. noun1 •(informal) Ellipsis of subdural hematoma. formssubdurals