Noun windfall has 2 senses
  1. windfall - fruit that has fallen from the tree
    --1 is a kind of
    edible fruit
  2. boom, bonanza, gold rush, gravy, godsend, manna from heaven, windfall, bunce - a sudden happening that brings good fortune (as a sudden opportunity to make money); "the demand for testing has created a boom for those unregulated laboratories where boxes of specimen jars are processed lik an assembly line"
    --2 is a kind of happening, occurrence, natural event