Well, Baby Boomers are a formal cohort...but there are also microgenerations -- such as the "Leapers" who straddle the gray area between the youngest Traditionalists ("The Silent Generation") and the oldest Boomers...or the "JonesGens" ("Generation Jones"), who straddle the gray area between the youngest Boomers and the oldest Xers:

https://medium.com/indian-thoughts/skimming-the-generational-fringes-bb0f602b1d8e