headroom [ˈhɛdˌrum, -ˌrʊm]

例句:

• The Sport is stingy on headroom for the driver.
  来自WSJ
• There's a lot of headroom for such a small car.
  这么小的一辆汽车的头上空间蛮大的。
  
• There is not enough headroom for buses to go under this bridge.
  这座桥梁下面的净空高度不够,公共汽车不能通行.
  
• Carry headroom to provide technical equipment standard.
  提高空管技术装备水平.
  
• You can now find Headroom's information, support and videos on other areas of the BBC website.
  来自BBC
• I had plenty of headroom, but I would have to lose an inch or two of personal width to feel really comfortable.
  来自WSJ