ice-nine but for concepts. someone invents a newer, shinier purple and once you see it you're completely incapable of seeing regular purple as anything but the new stuff
someone says the New Hello to you and you can't even remember the words to the Old Hello. you're sure you knew it once, but the memory is simply replaced with the New Hello. you greet someone and the New Hello comes out your mouth
This kind of literally happened with goodbye.
How many people know it started as a written abbreviation of "G-d be with ye"?
It isn't as dramatic as a new thing suddenly and spontaneously annihilating an old piece of language, but on a zoomed out enough timescale, it kind of did.
