1. [informal] Expresses extreme surprise, shock, dismay, awe, etc.
   "yow! I can't believe we won the lottery!";
   - oh my God [informal], my God [informal], omigosh [informal], ohmigod [informal], ohmygod [informal], omigod [informal]
    
2. Expression of pain
   - eina [S.Africa], ouch, ow

Encyclopedia: Yow, David