theantipam asks: What are the rules for compound words and plurals?
With examples from Stargate SG-1 and Harry Potter
Compound words are typically made up of adjectives and nouns, although the more simple ones are created from two nouns. Deciding which word should be the plural can be difficult, but perhaps the following guidelines will make things a little easier for you.
Compound words come in three forms: closed, hyphenated and open. Closed forms are single words that are made up of two, such as firefly, matchbox, steamboat, boxcar, and notebook. These are the easiest compound words when adding a plural. Just apply the plural to the end of the word.
Harry couldn't help but wonder how many other werewolves roamed the Forbidden Forest.
Hermione watched as Mrs. Weasley dropped spoonfuls of sugar into her tea, while the pot on the table trilled a cheerful tune.
Hogwarts catered to muggle-born schoolchildren as well as those from pureblood families.
The hyphenated form is just that - words that are connected by a hyphen. Examples include brother-in-law, commander-in-chief and jack-o-lantern. The basic rule when adding a plural to these words is to add it at the end of the most important part of the word, the noun, which is the word that can be described or modified.
"Having several mothers-in-law is not a blessing," Jack said, as he watched one of the natives walk away from a group of bickering women.
The Goa'uld were defeated. They were reduced to a battery of has-beens that no longer held any power over the Jaffa.
Open forms are two or more words that are regarded as a unit, such as court martial, post office and attorney general. These words can be made up of two nouns, a noun/adjective or an adjective/noun. As in the hyphenated form, the plural for these words are applied to the most important part, which in most cases is the noun.
Several attorneys general stood around the table, waiting for General Hammond to make his statement for the defendants, Colonel O'Neill and Major Carter, who faced charges of insubordination.
The courts martial of both officers created a field day for every newspaper journalist in the country.
The joint chiefs of staff demanded to meet with Hammond and several other major generals associated with Stargate Program to discuss the merit of sending extra troops through the Gate.
A quick note on the above examples: when determining whether the word, "general" should be plural in a compound word, such as attorney general and major general, just remember that a military general is way more important than a civilian general. This is why the plural should be added to the word general in a military title, such as brigadier generals, while the plural for a civilian title becomes advocates general.
To sum it all up, adding the plural to the noun (or the most important part) of the compound word is the key to getting it right. And when two words team together to make one, add the plural at the end.