Does the abbreviation pp stand for “plural pages,” or is it just a more-than-one-page, more-than-one-p idea? My Google-fu is coming up empty on anything I’d consider definitive.
It simply means multiple pages; it is not an abbreviation.
Spanish does this as well; the abbreviation for Estados Unidos (United States) is EEUU.
Multiple pages, simple as that. This usage comes from Latin. See bibliophage’s answer in this old thread.
At one time, to pluralize an abbreviation, you doubled it (or a part of it). “p. 93” means “refer to page 93” while “pp. 93-7” means “refer to pages 93 to 97.” The “cc:” at the bottom of letters technically means “copies to the following,” though in modern usage even a single copy is annotated that way.
Similarly, a reference to “p.93f” means “refer to stuff on page 93 that’s continued on the next page” while “p.93ff” means “refer to stuff beginning on page 93 and continued in passing on several following pages.”
Although I don’t understand the details, there’s a similar case (whether current practice or in desuetude, I’m not sure) with an abbreviation used in notarization, where something like “L.S.” means, in effect, “I witness this as a notary in this particular jurisdiction” while “L.SS.” means, similarly, “I certify that I witness this as a notary whose certification of it is valid in more than one jurisdiction in which this document will be legal evidence.” Someone familiar with notary law would have to explain that one a bit more clearly than that, but you get the general idea.
My understanding is different; that “cc” stands for “carbon copy.” No cite, but that’s what my typing teacher told me in 1974, when she was showing us business-letter format and how to use carbon paper. The “cc” at the bottom of manual/true-carbon letters has simply been carried over, having achieved an idiomatic meaning of its own.
This is supported by Merriam-Webster:
It was originally to indicate those people to which carbon copies would be sent, besides the addressee, who would get the original.
Now they tell me the “cc:” is for "courtesy copy, because carbon’s have gone the way of the dodo.
As to the OP, the doubling thing is not uncommon – along with pp, there’s also the double section and paragraph marks to refer to multiple sections or paragraphs, and when you want to refer the reader multiple places, q.v. becomes q.q.v. (Or is it q.v.v.? I can never remember.)
–Cliffy
I believe it was a Latin custom to indicate plurality of an abbreviation by doubling the last letter. One can still see this being practiced in Spanish, where “Estados Unidos” for example is abbreviated “EE. UU.”
:smack: And now I see that Colibri already said the same thing. Must…read…thread…more…carefully…
So? It still stands for “carbon copy,” whether carbon paper is used or not. “cc:” = “Copies sent to:” The fact that there’s no carbon paper is irrelevant.
I’m with you, Chuck, but the tide is rushing forwards nonetheless.
–Cliffy
I’ve seen a similar notation used for scripture references that span multiple verses, i.e. John 3 vv16-21.
And in botany a statement referring to multiple species of (say) the genus rubus may be written rubus spp.
{and similarly to Colibri’s comments in support}
My understanding is that that is “folk etymology,” an explanation originated by people unfamiliar with the doubling-for-pluralization custom, which has since gained the weight of authority (such as G. & C. Merriam & Co.). However, I don’t want to make a major issue of it. Perhaps the three of us can discuss it someday, over a dinner of Welsh rarebit? 
I haven’t been able to find anything to support this by Googling. If this was the case one would expect to find the notation on manually written copies that predated the invention of the typewriter. Does the OED cover abbreviations?
A related abbreviation is “fcc” for “first carbon copy,” to indicate the first, and therefore clearest, carbon copy of several that were made of the same typed letter. (For those too young to remember carbon paper, several layers of paper and carbon paper could be rolled into the typewriter, but the lower copies were much fainter due to padding of the keys by the paper layers.)
Just to nitpick, that’s not “folk etymology”; it’s an urban legend about the etymology of the word.
“Folk Etymology” is a term used to indicate that an unfamiliar word taken from another language is changed to be more comprehensible in the new tongue. For instance, “turtle” is the result of folk etymology – it’s taking the French term “tortue” and changing it to match an already familiar word: “turtle” (now known as “turtledove.”) “Isinglass” is another example, coming from “huizenblas.” There’s also the Picketwire River in Colorado, derived from the French “Purgatoire”
From the OED:
1936 L. I. HUTCHINSON Stand. Handbk. Secretaries 287 The carbon copy notation, ‘*c.c.’, should be the last notation. 1969 M. PUGH Last Place Left iv. 22 Have you seen the letter?.. It says c.c. to you. Carbon copy. 1982 Computerworld 23 Aug. 33/3 You may sometimes want to keep others informed of what you are asking a person or group to do. In that case, indicate it as a ‘carbon copy’ (CC) on the bottom of the memo.
To be fair, etymologist John Ciardi used the term colloquially as Polycarp did.
Happens in legal writings as well. s.167 (section), ss. 157-160.
As RealityChuck noted, “folk etymology” doesn’t have to mean the actual changing of a word to conform to a more intuitive “folk” explanation of its origins.
“Folk etymology” is also correctly used to mean that more intuitive explanation itself. For example, saying that the expression “poll tax” derives from “polls” as in voting (when the actual derivation is almost the other way around) is an example of folk etymology, even though the word “poll” hasn’t been altered in the process.
I’ve sometimes seen the term “hobson-jobson” used for a word that’s been altered in a folk-etymological way, like “belfry” from “berfry”, although it more commonly refers to a corrupted loan word from a foreign language.
And I too am skeptical of the claim that “carbon copies” is a folk-etymology interpretation, and that “cc” was originally simply a plural form like “pp”.
(Hmm, if that claim is indeed incorrect, would it be an instance of folk etymology itself? Maybe we need a specific term for incorrect etymological explanations that suggest falsely erudite derivations, and incorrectly disparage the true derivations as “folk etymology”. “Snooty-folk etymology”, perhaps? :))
Or “snob etymology”? “Pedant etymology”?