[mass noun]a black viscous mixture of hydrocarbons obtained naturally or as a residue from petroleum distillation. It is used for road surfacing and roofing 沥青 ■(Austral. informal)a tarred road surface (澳, 非正式)柏油路 a kilometre and a half of bitumen. 一公里半的柏油路。
语源
late Middle English (denoting naturally occurring asphalt used as mortar): from Latin