That is, is there a term to specifically distinguish the type of thing x is, as juxtaposed with x', x'', etc?
The wikipedia page on the prime symbol mentions that "The prime is said to "decorate" the letter to which it applies.", which gives me that idea that perhaps "undecorated variable" is the term I'm looking for, but I haven't found any examples of people using it. Is there a standard term for this?