Coincidence.
Coincidence is a meaninglessly simultaneous occurence. Synchronicity, a relatively new word, implies that there is meaning to it.
Coincidence, meaning the occurrence of events that happen at the same time by accident but seem to have some connection from the Merriam-Webster dictionary. You can remember by thinking Co- (meaning together) and -Incidence (meaning an event).
The closest synonym is coincidence, but fortuitous coincidence is closer if you don't mind using two words.
Coincide
Coincidence.
It's coincidence.
The correct spelling is "coincidence" (happenstance, synchronicity).
coincidence http://dictionary.reference.com/browse/coincidence
COINCIDENCE - a chance relationship between dissimilar events or circumstances
The likely word may be the noun coincidence (a chance or random occurrence). The adjective form is coincidental.
Coincidence
It was just a coincidence that I ran into my old friend at the grocery store yesterday.
The adverb for the word coincidence is coincidentally.
There is no saint of coincidence in the Catholic Church.
The Roots of Coincidence was created in 1972.
Chance or Coincidence was created in 1998.