1. 拦截;拦住
If you head off a person, animal, or vehicle, you move to a place in front of them in order to capture them or make them change the direction they are moving in.

2. 阻止，防止（尤指不愉快的事）发生
If you head something off, especially something unpleasant, you take action before it is expected to happen in order to prevent it from happening.

1. prevent the occurrence of
prevent from happening

e.g. Let's avoid a confrontation
head off a confrontation
avert a strike

Synonym: debarforefendforfendobviatedeflectavertstave offfend offavoidward off