• something blown down by the wind (e.g. fallen fruit); find, unexpected good fortune; unexpected inheritance
• a windfall is a sum of money that you receive unexpectedly.
• deficit that was not predicted in advance, large and surprising loss
had a windfall
• obtained something without effort, had an unexpected piece of good fortune, received an unexpected gain
having a windfall
• obtaining something without effort, having an unexpected piece of good fortune, receiving an unexpected gain