1. v. When a vehicle or machine decelerates or when someone in a vehicle decelerates , the speed of the vehicle or machine is reduced.降低速度;减速行驶（或运转）
2. v. When the rate of something such as inflation or economic growth decelerates , it slows down.(通货膨胀、经济增长等的速度)减缓，放慢
decelerate同源
accelerate
1. v. If the process or rate of something accelerates or if something accelerates it, it gets faster and faster.（使）加快；（使）增速
2. v. When a moving vehicle accelerates , it goes faster and faster.（行驶中的车辆）加速
acceleration
1. n.[U] The acceleration of a process or change is the fact that it is getting faster and faster.加快；增速
2. n.[U] Acceleration is the rate at which a car or other vehicle can increase its speed, often seen in terms of the timethat it takes to reach a particular speed.（汽车等的）加速能力，加速幅度
3. n.[U] Acceleration is the rate at which the speed of an object increases.加速度
accelerator
1. n.[C] The accelerator in a car or other vehicle is the pedal which you press with your foot in order to make the vehicle go faster.（汽车等的）加速装置，油门
