n
(a) [C] track for fast driving and racing, esp by motor-bikes 赛车跑道（尤指摩托车的）.
(b) [U] sport of racing motor-bikes on such a track 摩托车赛
*Do you like speedway? 你喜欢摩托车赛吗?
(c) [C] (US) road on which fast driving is allowed 高速公路.

n
[U]
the sport of racing motorcycles or cars on a special track
[C]
a special track for the sport of speedway