1. As soon as
   "when we are home, we can rest";
   - once
    
2. At what time?
   "When are you coming home?"
    
3. In what situation
   "close the door when you're finished"

1. At the same time that
   "they were walking home when they were discussing the problem";
   - as, while, whilst [Brit]
    
2. Every time that
   "when I call you are always engaged";
   - if, whenever

Sounds like: whelp, wh

Encyclopedia: When