The idea that the entirety of history and existence is a series of repeated events; nothing that happens is new. The idea implies events are connected circumstantially through their meaning, and from a temporally external frame of reference, happen at the same time. The term was coined by Andrew Hussie in his webcomic Homestuck.
Alice: I broke my wrist last week after slipping on an acorn. Didn't that same thing happen to you?
Bob: Indeed. It's wondrous how rampant circumstantial simultaneity is throughout the universe.
Alice: bob stfu you fucking nerd