noun. An egotist.

His Works hereafter will be more favourably receiv’d..by the Meists and Selfists.
Common Sense (1737)

A meist (or me-ist) is someone who subscribes to some form of me-ism. You know the type. Maybe you are the type. I don’t know, you tell me: are you a youist?

Hey, it’s another perfect name-calling word. Oh frabjous day! Callooh! Callay! Now you can call all the big-headed people you know meists. You can nickname the most meistiest one the meist-meister!

The confusing thing is who you’re referring to when you say it. If I say, “I’m a meist!” that of course means that I’m full of myself. But if I ask, “Are you a meist?” couldn’t I be asking you if you’re full of me? I could say youist, but then it’s unclear if the person I’m referring to is full if him/herself or others.