At the end of Avengers: Infinity War, after Thanos had finally collected all six Infinity Stones, the Mad Titan proceeded to snap his fingers and half of all life in the universe ceased to exist. Since the movie came out, we have all referred to it as "The Snap" or "The Snappening," but that stops today. Marvel has finally given an actual name to the event.
In the Avengers MCU prelude comic, which was released this week, the event was referred to as "The Decimation." So, in the Marvel Cinematic Universe, this is the name given to the Snap by those who witnessed it.
While this certainly sounds like a terrifying name, it doesn't make a ton of sense when you really think about it. By definition, the word decimation means "the removal of a tenth." Thanos removed the population of the universe by an entire half. The numbers don't really add up there.
No matter what it's called, Thanos' removal of half of all life will forever go down as the most devastating event in human history (within the MCU). As we learned in Infinity War however, that event didn't come without a cost.
In addition to the loss of Gamora to the Soul Stone, Thanos also suffered physical injuries as a result of his actions. During a recent Q&A after a screening of Infinity War, directors Joe and Anthony Russo were asked about the toll the "Decimation" took on Thanos when it was all said and done.
“It’s evident,” Joe said. “His daughter is an emotional price, but the physical price is - you’ll see it if you pause your DVD - right before he uses it to go back into the portal away from Thor while he’s got the ax in his chest, his arm is burnt to a crisp. So the physical price is the extreme power that it took to enact his plan, he paid for physically, and when he sits down on the steps at the end of the movie you can see that it actually carries up into his neck and onto his face.”
The rest of Thanos' story will unfold in Avengers 4, which hits theaters on May 3, 2019.