1) an adaptive response to catastrophe, provided that catastrophe is suitably devastating enough to necessitate real change and not nearly so apocalyptic as to make recovery impossible.
2) renewal of human society in the aftermath of a disaster, somewhat hopeful in that it assumes a creative flourishing, a renaissance if you will, is in the offing, provided that we possess the ability, the wherewithal, and the willingness to learn.
3) in biology (somewhat archaic): the evolution of a species toward a simpler, less specialized form, often in response to environmental stress.
4) in geology: the natural chemical process by which complex organic compounds called kerogens break down into less complex compounds called hydrocarbons, which we then drill for, suck out of the ground, and process further into a plethora of petrochemical products—various fuels, for instance, which we use to cook our food, heat our homes, power the turbines that generate our electricity, and feed the machines that that do the work that make our world possible.
Used in a sentence (really it’s more implied; never got around to actually using it):
As implied in the following sentence :
When virtuous becomes vicious, when society gets stuck in an all-consuming cycle of growth for the sake of growth, when this perpetual motion mass extinction machine chuga-chuga-choo-choos on, when we fail to read the flashing warning signs, when we do plunge headlong off that cliff, when the inevitable disaster is compounded by inevitable disaster, when our failing institutions perform as poorly as can be expected, when we set upon each other like the confused beasts that we are (and always were), when we place the blame, as ever, elsewhere, when we sacrifice our fattened scapegoats, when the Four Horseman ride us down and then ride on, when there is no sign of a god-appointed Savior and no goddamn hope to be found, when we, nevertheless, have our come-to-Jesus moment, when we are forced to confront the wages of our collective sin, if we—the ashen survivors—then commit ourselves to learning all that we can from our failure, if we salvage what was useful and good from the derailed wreckage of our world as it once was, if we can call forth enough courage, then maybe we can do more than stumble about our ruin like haunted ghosts; we might even build it all back, even better than before.
Note: You will not find definition 1 or 2 in your dictionary. The word catagenesis was plucked from relative obscurity and repurposed by Thomas Homer-Nixon in his book The Upside of Down: Catastrophe, Creativity, and the Renewal of Civilization.