Paul Beakley has defined two new rpg theory terms which I think will be useful.
The Transaction — “The steps players engage in to settle outcomes in the fiction. … a subset of the much larger conversation in which all the play takes place.”
I don’t think that definition is particularly instructive, but the worked examples he gives in his post (for Scum & Villainy, Burning Wheel, and Apocalypse World) are much more so.
Rawplaying — “Playing an RPG by the rules because we earnestly feel the rules produce the best experience for us.”
The term is useful to me because while it’s not always what I do, it’s very often what I try to do. And there’s a big divide in rpg culture between people who take this seriously and people who don’t.
The Wrong Kind of Wax 
I think there’s three sides here:
Side A who tries to play RAW
Side B who doesn’t care about the rules and changes them to fit the moment
And Side C that uses pieces of rules from different sources but uses them RAW