/ˈhedru:m ||; ˈhɛdˌrum/noun [U]:
1 the amount of space between the top of a vehicle and an object, for example a bridge, that it drives under 净空高度（指车顶与物体之间的空间，如从桥下驶过时与桥之间的距离）
2 the amount of space between the top of your head and the inside roof of a vehicle 头上空间（指头顶与车篷内侧之间的距离）