Coincidence
Part of speech: noun
Definition: Of objects, the property of being coincident; occurring at the same time or place. Of events, the appearance of a meaningful connection when there is none. A coincidence point.
Example sentence: Many applications of the coincidence method will therefore be found in the large field of nuclear physics, and we can say without exaggeration that the method is one of the essential tools of the modern nuclear physicist.
Happenstance
Part of speech: noun
Definition: A chance or random event or circumstance.The chance or random quality of an event or circumstance.
Example sentence: As for 'Great Expectations', it is up there for me with the world's greatest novels, not least as it vindicates plot as no other novel I can think of does, since what there is to find out is not coincidence or happenstance but the profoundest moral truth.