Synonyms for Downfall (same or very similar meaning)
WordNet sense 1 (the falling to earth of any form of water (rain or snow or hail or sleet or mist)):
precipitationWordNet sense 2 (a sudden decline in strength or number or importance):
fallWordNet sense 3 (failure that results in a loss of position or reputation):
ruin, ruinationFrom the ODE community, based on WordNetadd/edit