godsend

noun

1. An instance of unexpected benefit or good fortune; a windfall.

   “"You do, indeed, seem to take it to heart!" exclaimed the actress, an expression of jealous anger crossing her features; "why, it is quite a God-send for you! many a heart is caught in the rebound.[…]"”

   “[O]nce again, as in 1803, we were on the brink of being sacrificed to the very lunacies of retrenchment. By a mere god-send, more troops happened to arrive from the Indian continent.”

   “By this time my wife was in Barcelona and used to send me tea, chocolate, and even cigars when such things were procurable; but even in Barcelona everything was running short, especially tobacco. The tea was a godsend, though we had no milk and seldom any sugar.”

   “To the onlooker, and particularly to those whose memories go back to pre-grouping days, the modern cavalcade of "V2s" and "B1s" is apt to become a little monotonous; but to any running man the general utility characteristics of these two classes are a perfect godsend at times of exceptional pressure, when it is often a case of "first in—first out" with locomotive allocations at sheds.”

2. (British, archaic, regional, specifically)An instance of unexpected benefit or good fortune; a windfall.

   “Its seldom sic [such] rich Godsends come on our coast—no since the Jenny and James came ashore in King Charlie's time.”

3. A person who provides greatly needed assistance.