When coined in the late 19th century, happenstance, a fusion of happen and circumstance (with chance perhaps also in the mix), was a light neologism in the vein of newer words like ginormous and guesstimate. But happenstance apparently filled a gap in the language, and it caught on. By the first decade of the 20th century, it was already being used in earnest in many American publications.
Happenstance means (1) chance or (2) a chance occurrence, but it has subtleties of meaning that differentiate it from chance. Whereas something that happens by chance may come out of nowhere, happenstance derives from a confluence of circumstances and may be more predictable than pure chance.
Happenstance is originally American. Though its exact origins are unknown, it appears to have come about in the middle to late 19th century. Several sources list this passage from a story by Minetta Eames, published in an 1897 issue of Outing magazine, as the earliest known use of the word:
“I guess it was just a ‘happenstance,’” Sam said, with an adroit wink and a thrust of his tongue. “Generally a man don’t wait to see a deer, but just shoots at what might be a part of one.”
But a Google Books search reveals several earlier examples. We’ll include a few of these below, along with a few recent ones.
Among the “adventures,” which are of daily occurrence at places where ladies and gentlemen congregate, with the expectation of being and doing the exquisite in the matter of politeness, the following account of a recent “happenstance” at Trenton Falls, communicated by a correspondent of the New York News, will do to put on record. [Supplements to the Connecticut Courant (1855)]
Spencer gives a supposed case of an animal, that by some happenstance got an unusually heavy head, and then supposes that natural selection preserves it. [The Problem of Problems, and Its Various Solutions, by Clark Braden (1879, USA)]
This is of course a very brief account of the happenstance, but the enterprise was a success. [Glimpses of the Life and Times of A.V.H. Carpenter, by Albert von Haller Carpenter (1890, Chicago, USA)]
Perry detractors argue Perry is merely the inadvertent beneficiary of luck and happenstance. [Forbes]
[B]y glorious happenstance, I had a pack of tissues in the back pocket of my trusty jeans. [Scotsman]
In a weird bit of happenstance, the three most impactful non-boxers in the sport of the last four decades each turn 80 this year … [CBC]
I was born there. I grew up there, and through a succession of life choices and happenstance ended up here. [Stuff.co.nz]