The term "generational" does get used to oblivion on HFB.
In recent memory I think the following players qualify: Gretzky, Lemieux, Crosby, Ovechkin, McDavid, arguably Lidstrom, Jagr, Roy, Hasek.
Eric Lindros would have qualified with better health.
Brett Hull, Zdeno Chara, Getzlaf, Erik Karlsson, Patrick Kane, Chris Pronger, Carey Price, Nikita Kucherov, and Nathan McKinnon are the next level down.
I assume without proof that Bedard, Celebrini, and Demidov will belong in the second group if everything goes right for them.