downfall in WordNet English dictionary

1. a sudden decline in strength or number or importance
   "the fall of the House of Hapsburg"
   fall  downfall 
   
2. failure that results in a loss of position or reputation
   downfall  ruin  ruination 
   
3. the falling to earth of any form of water (rain or snow or hail or sleet or mist)
   precipitation  downfall