Because I just made a post in which I use some of them, so I should probably define them.
Narrative Power Dynamic: A power dynamic in a narrative, whether this narrative is a story being read, a roleplay, someone’s description of their preferred power dynamic, etc. I might sometimes just say power dynamic.
Principal: The ‘top’ in a narrative power dynamic. When talking about roleplay, I call the person playing the principal ‘P‘.
Constrict: (as in, the noun form of ‘to constrict’, the difference in pronunciation like the one between ‘to present’ and ‘a present’). The ‘bottom’ in a narrative power dynamic. When talking about roleplay, I call the person playing the constrict ‘C‘.