The concept of the “Overton window” was coined by a think-tank guy in a 2010 book while making a pretty obvious observation. It took off in the mid 2010s and has skyrocketed in general use in the years since, as first pretentious podcasters and then political commentators of all stripes began using the phrase casually. It is, of course, no coincidence that this all coincides with the rise of the political career of one Donald Trump.