What Does Pre-empted Mean?

The word pre-empted is the past participle of the word pre-empt and the word can be used as a verb. The phenomenon it describes is to prevent something happening by taking an action to stop it. Given below is a sentence that can help you in understanding the word quite well: A good training course can prepare you to handle any problem that is expected to arise when you are handling the actual situation.
        
The word can also be used to convey an idea of doing something before someone else does it. The following sentence can make the meaning of the term quite clear in this context: John was about to apologize when Stella had pre-empted her. In the above mentioned sentence the idea is that Stella had apologized before John.  
      
Sometimes the word cab also is used for the phenomenon of replacing the earlier planned programme on television.