Thanos' Infinity Stone-powered snap wasn't just a monumental moment for the MCU but it has slowly become a big part of pop culture, which is pretty crazy. It's one of the reasons why Avengers: Infinity War has become as big as it is now and we're all just here impatiently waiting for the sequel, which still doesn't have a name. Interestingly enough, a tie-in novel has given the Thanos snap a name but we're not sure if it will stick.
According to The Cosmic Quest Volume 2: Aftermath (via Screen Rant), people within the MCU are calling Thanos' snap "The Decimation," which actually sounds like a comic book event. It's also a pretty accurate description since the snap literally decimated half of the universe's living being, so it's not just a melodramatic cheesy description.
Only time will tell if this will stick and get referenced in Avengers 4, though it would be nice if it would. Granted, calling it "The Snap" would still be effective and resonate with everyone who watched Infinity War but "The Decimation," is far from a bad name.
Keep in mind that Marvel hasn't always made their tie-in material canon with the larger MCU. The Thanos origin novel that came out after Avengers: Infinity War was supposed to be the character's origin but now it's non-canon since Marvel might want to tell that story themselves.
Avengers 4 comes out on May 3, 2019.