Apostrophe Catastrophe (Part Two)

How to make singular and plural words that end with S possessive. It's an apostrophe style choice.

Mignon Fogarty
5-minute read
Episode #713

You didn’t realize it at the time, but last week was part I of apostrophes, and today is part II. Today's topic is tough apostrophe issues.

How do You Make Singular Words Ending in S Possessive?

I said it in the last episode about apostrophes, and I'll say it again: there are some confusing situations when it comes to apostrophes. For example, Christine, from Portland, Oregon; Judy from Traverse City, Michigan; Katy from Australia; Kristi from Washington, D.C.; and Rick from Las Vegas, Nevada, all asked how to make a singular word that ends in S possessive.

I know that this is a raging debate even at the highest levels of government because Tracey from Mountain View, California, and a listener named Arman both sent me a funny article a while ago describing U.S. Supreme Court squabbles over making the word "Kansas" possessive. Words such as “Kansas” that end with an S can be stumpers when it comes to apostrophes.

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Is it “Kansas's statute” with an apostrophe-S or “Kansas' statute” with just an apostrophe at the end? 

Justice Clarence Thomas wrote the majority opinion and left off the extra S, referring to “Kansas' statute” with just an apostrophe at the end, whereas Justice David Souter wrote the dissenting opinion and used a double S at the end of “Kansas,” writing about “Kansas’s statute” with an apostrophe before the final S.

So who's right? Well, they’re both right, and they really should have a Supreme Court style guide so their writing is consistent. They’re both right because this isn’t a rule; it’s a style choice. Justice Thomas, whose name ends with an S, seems to favor AP style, which recommends leaving off the extra S. 

AP style is Kansas’ 

Chicago Manual of Style Apostrophe Rules

Justice Souter seems to prefer the recommendations of The Chicago Manual of Style, which says to add the apostrophe-S to almost all singular nouns and names that end with S. 

Chicago style is Kansas’s

Chicago Manual of Style Apostrophe Exceptions

Chicago used to make exceptions for names with two or more syllables that end in an “eez” sound and nouns or names that end with an unpronounced S. So they were saying you should write names like “Euripides” and “Descartes” with only an apostrophe and no extra S on the end. So you may have heard those rules, but the editors reversed their decision in the 16th edition of the stylebook. 

So now there are only two exceptions in Chicago for making words that end in S possessive: 

First, you still use a lone apostrophe to make what they call “uninflected nouns” possessive. Those are the rare birds for which the singular and plural are the same and end in S—so words like “politics” and “economics.”

Second, you still use a lone apostrophe when making place names that end in a plural ending with S possessive, like “the United States” and “Beverly Hills.”

So you’d write about “Beverly Hills’ recent tax hike” and “politics’ downside,” and both of those would have just an apostrophe and no extra S at the end of “Beverly Hills” and “politics.”

Whew, so that seemed complicated, but remember most of the time it’s simple. In AP style, you use a lone apostrophe to make singular nouns and names that end with S possessive, and in Chicago style, most of the time you add an apostrophe and an S, with a few rare exceptions.

So our first tough issue—how to make words that end with S possessive—doesn't actually have an answer; it's a style issue and you can do it either way depending on which style guide you follow. But at least it’s simpler than it used to be.

What About Plural Words?

I always feel bad when the answer is that there isn't an answer, so here's an easier situation that has a firm rule: If the word ending with S is plural, such as “aardvarks” when you’re taking about more than one aardvark, then you just add an apostrophe at the end to make it possessive. For example, you could write, "The aardvarks' escape route was blocked,” to indicate that a family of aardvarks needed to find another way out of danger.

If the word ending with S is plural, add an apostrophe at the end to make it possessive: the aardvarks' route.

Plural words that don't end with S, such as “children,” do take an apostrophe-S at the end for possession. For example, you could write, "Fortunately, the children's room had a hidden doorway,” with “children’s” written as “children apostrophe-S.”

Apostrophes for Single Letters

Here's another tricky issue with a definite answer: How do you make the plural of a single letter, as in “Mind your P's and Q’s?" It's shocking, but you actually use the apostrophe before the S! It looks possessive, but it isn't. The apostrophe is just there to make it clear that you're writing about multiple P's and multiple Q's. The apostrophe is especially important when you are writing about A's, I's, and U's because without the apostrophe readers could easily think you are writing the words “as,” “is,” and “us.” (That reminded me of what we talked about last week with single letters being referred to with the phrase “per se” when they were being used as a word instead of a letter, like “I, per se I” to mean the word “I.”)

Use apostrophes to make single letters plural: Mind your p's and q's.

Note that you can write the single letters capitalized or lowercase. We capitalize single letters on this site, but AP style uses lowercase letters in a phrase like “Mind your p’s and q’s, and uppercase letters for letter grades such as “He got all A’s.” Chicago follows the same capitalization style, but omits the apostrophe from letter grades: “He got all As.”

Should You Use Apostrophes with Abbreviations?

Finally, we'll end with another gray area. Brian in Toronto and a listener named Josh asked whether they should use apostrophes to make abbreviations plural. Brian gets irritated when he sees signs advertising “CD's for sale” with it written C-D-apostrophe-S. Gen wrote in about the same thing, feeling a sense of horror after seeing “CD’s” written with an apostrophe in The New York Times. 

Don't use apostrophes to make abbreviations plural: CDs.

Years ago, this used to be a style choice, and it was quite common for style guides to recommend using an apostrophe to make abbreviations plural, but as time went on, more and more style guides stopped recommending the apostrophe. And it’s even more complicated than that. 

For example, along the way, in early 2010, The New York Times and The Chicago Manual of Style used an apostrophe to make abbreviations that included periods plural, but not abbreviations without periods. So in The New York Times, you would see “M.D.’s” for the plural of “M.D.,” but “PCs” for the plural of “PC” for “personal computer.” But even they stopped this practice sometime later. Today, The New York Times style guide and The Chicago Manual of Style both say not to use apostrophes to make abbreviations plural, whether they have periods or not. 

Original courthouse image, noahjeppson at Flickr. CC BY-SA 2.0

About the Author

Mignon Fogarty

Mignon Fogarty is the founder of Quick and Dirty Tips and the author of seven books on language, including the New York Times bestseller "Grammar Girl's Quick and Dirty Tips for Better Writing." She is an inductee in the Podcasting Hall of Fame, and the show is a five-time winner of Best Education Podcast in the Podcast Awards. She has appeared as a guest expert on the Oprah Winfrey Show and the Today Show. Her popular LinkedIn Learning courses help people write better to communicate better.