the force or action of one object hitting another

The impact of the crash reduced the car to a third of its original length. 撞车时的冲击力使车身变形，仅剩原长的三分之一。

The bullet explodes on impact (= when it hits another object). 子弹击中物体时爆炸。

a powerful effect that something, especially something new, has on a situation or person

The anti-smoking campaign had had/made quite an impact on young people. 禁烟运动对年轻人影响很大。

The new proposals were intended to soften the impact of the reformed tax system. 新的提议旨在减轻改革后的税制所造成的影响。

to have an influence on something

Falling export rates have impacted (on) the country's economy quite considerably. 出口率的下降对该国的经济造成了相当大的影响。