Is there any logical reason or rule that would explain why words like this are not “Attorney Generals” in the plural?
And is there a name for these double words that require this type of plural?
It does not apply to titles such as Vice Presidents or Lt. Governors and others.
Because Attorney is the noun, as is President and Governor.
ETA - see also, mothers-in-law.
“Attorney” is the noun, “General” is an adjective, in this case.
We could call attorneys general “general attorneys” (the attorney tasked with representing the legal interests of a sovereign entity in all matters) and it would mean the same thing.
But we wouldn’t call them “generals attorneys,” any more than you would see a group of shaggy dogs and say “look at those shaggies dogs”
General is not a noun? :eek:
ETA: Whoops, I wrote this before I saw the other replies that explained it. Sorry
“Attorney General” is an example of a postpositive adjective. Postpositive adjectives follow the nouns they modify in accordance with Romance syntax rather than Germanic syntax that English normally follows. They’re usually found in English as a remnant of Norman French influence during the Middle Ages, especially right after the Norman Conquest.
French legal phrases, syntax and all, were adopted into English unchanged, even though in English adjectives almost always precede the nouns they modify. A few examples of legal phrases with postpositive adjectives: accounts payable, accounts receiveable, attorney general, condition precedent, condition subsequent, easement appurtenant, fee simple, president-elect, court martial, queen regnant, heir apparent, body politic, sum total, notary public.
(Source: Bryan E. Garner, A Dictionary of Modern Legal Usage 424-425 (1987).)
Not here. Or at a General Store.
Sometimes it is. Sometimes it isn’t.
“I’m a general in the Army” = “general” used as a noun
“I’m a colonel in the Army, and I live in this general area” = “general” used as an adjective.
Oh, and if you ever want to come off like a pedantic dick, go into a Taco Bell and order up some Burritos Supreme.
Or go to a Burger King and order two Whoppers Junior.
But it’s fine to go to an upscale restaurant and ask for some filets mignon. (Or even filets mignons if you want to be closer to the French.)
Note that your army general is really just an abbreviated way of saying “general officer.” So it has become a noun because the real noun deserted it. 
nm
However, you would in Spanish. In Spanish adjectives get assigned the number and gender of the noun they modify (though not all adjectives have separate gender forms/spellings) Abogados generales (attorneys generals), with attorney as the noun) would be a literal translation, though I don’t know what Spanish speaking countries actually use that as a title.
My understanding was that it originally wasn’t - it was an adjective that modified “Officer”. A “General Officer” was one who could pretty much be assigned authority over anything and had general authority over all subordinate officer types, while a Colonel or a Lieutenant was restricted in what they could command, e.g. a Lieutenant might not be allowed under military laws or regulations to be placed in command of a full regiment or a whole base. Can anyone find a cite?
Similarly, in the case of Governors General, the French is gouverneurs généraux, with a plural marker on the adjective. Of course in English we have no way to mark an adjective as plural in the same way.
All of which I agree with. Which begs the question: in baseball, why is it not R’sBI?
The abbreviation becomes the noun. Maybe not entirely logical, but practical. Of course, you could always insist that everybody call them BIRs. Then start a morale-boosting campaign for your team: Beers for BIRs.
Once we refer to it by the initials, it loses that part of the grammar. Ditto for MREs or POWs. Some plural abbreviations omit the s entirely, because they’re never used in the singular: MPG, RPM.
Gah. 1L Property flashback. shudders
Is this how we get “Grands Prix” ?
Yes, it’s French and both words are pluralized.