My only problem with the term "Geriatric Millennial" is that it sounds so self-deprecating.

When referring to the microgeneration that us older Millennials share with the younger Xers, I think "Xennial" (phonetically "Zenn-ee-uhl," for those reading this who are unfamiliar with the term) is a more appropriate descriptor for our "cusper" status.

I've also heard "Zillennial" used to refer to the microgeneration shared by the youngest Millennials and the oldest Zoomers (i.e., the cusp of Gens Y&Z).