Windfall

[PussyCat]

Anything blown down or off by the wind, as fruit from a
tree, or the tree itself, or a portion of a forest prostrated by a
violent wind, etc.

[Marquetta]

A sudden happening that brings good [fortune] or a sudden opportunity to [make money].

A sudden unexpected piece of fortune. A profit from a business or other [sorts]. Huge profits without working for them. An unexpected sudden gain or advantage. A sum of money.

[Jason Yan]

An [unexpected] [acquisition].

[Julian]

Defines an [extra] amount of money, [benefit] or [support].

[Luis Fok]

An apple or other fruit blown down from a tree or bush by the wind.