directionlessadj.无方向的；无目标的directionn.方向；指导；用法说明；趋势；目标；管理directional scanning定向扫描direction instrument方向仪direction of traffic行车方向directional property方向性direction of advance前进方向direction of texture纹理方向Direction prohibited禁止方向direction derivative方向导数direction of arrival波达方向direction characters方向特性