Consider the following sentence (modified from here):
It is now widely accepted that an archaeal host likely gave rise to the cell proper.
(Talking about eukaryotic origins.) What exactly the grammatical role of "proper" is here? Is "cell proper" standing for the concept of "a proper cell" and thus "proper" is a postnominal adjective? Or is it an adverb meaning "properly"? I have the feeling that the former is closer to the truth. I understand that words representing attributes can be positioned after the noun, for example:
- money unspent
- heir apparent
- people unharmed
- star visible
- people responsible
though it seems to me that these are mostly verb derivatives that perhaps are shorthands for e.g.:
Every star (that is) visible (by an anonymous grammatical subject) is named after a famous astronomer.
Clearly, "proper" is not a verb and does not behave in this way. I'm sure I've encountred similar cases with other non-verbs, but unfortunately, nothing comes to my mind at the moment. Also, can you use "proper" (and related) any time postpositionally? Are these valid? If not, how should one cumulate adjectives with a postpositional attribute?
- This is an argument proper.
- This was a breakfast proper. (might be ok but too formal?)
- This was an English breakfast proper. (doesn't sound right at all)
- This was a breakfast English proper. (ugh)
So how is the very first example with "proper" to be understood? Is "proper" a special word that conveys some extra meaning here that I fail to grasp and which justifies its special position? Can someone provide some historical background and insight on this formula? Also, what other (non-verb) words can be used this way?
Please don't close this question being a duplicate of this or this because it isn't. I'm asking for the grammatical role of a specific part of the sentence, what kind of words can play this role (if not verb-derived) and why these particular words ended up with this somewhat special role. Unfortunately, the answers at
How to tell if an adjective is attributive or predicative [EFL context]? are either simply stating the fact that it is a postpositive adjective form (with no further context) or list a few examples but with no explanation and background at all.