A
fortunate unforseen circumstance. An unexpected perk as a result of any given chain of events.
An obvious melding of the words fortunate + unforseen + circumstance.
This word
originated as a forcumstantial product of a slip of the tounge by a friend attempting to say "Fortunate unforseen circumstance".
Its obvious poetry, and the way it trips lightly off the tounge make it a forcumstantial addition to any
cutting edge lexicon or meme cache.