How To Pluralize Acronyms

Acronyms are words formed from the first letter or letters of each word in a compound term. Technically, an acronym must be pronounced as a single word; when you say each letter individually, it’s an initialism. For the purposes of this article, though, I’m going to lump them together and just use the term acronym.

Lots of acronyms come from government or military organizations, like CIA, FBI, radar, POW, and MIA. Some come from text lingo, like ASAP, LOL, and OMG. You’ll see them a lot in medical writing, with acronyms like HIV, AIDS, and MD. Some super common ones that we use every day include p.s., BTW, FYI, and DIY.

All of this just goes to show that acronyms are all over the place, and I’m sure you’re used to using them in your everyday life. They seem simple enough, but there are a few pitfalls: For example, when do acronyms need periods between the letters? Which indefinite article—a or an—comes before the acronym? What is a redundonym, and why is it a problem? I’ve got posts answering all of those questions (just click the links to get answers!), but this one is all about adjusting acronyms when there’s more than one of the thing you’re referencing.

In other words . . . what happens when you need to make an acronym PLURAL?

The General Rule for Plurals

Most English nouns follow this rule for pluralization: Just add “-s.”

• dog —> dogs
• bed —> beds
• world —> worlds
• supermarket —> supermarkets

Of course, there is no shortage of exceptions:

• man —> men
• person —> people
• octopus —> octopi
• bus —> buses
• fish —> fish

I’ll definitely need to do a separate post about all the different kinds of abnormal plurals, but for the purposes of this post, you just need to know that adding “-s” is the most common way to make a word plural.

Sometimes Apostrophes Come Into Play

Most of the time, apostrophes indicate possession, not pluralization. However, in a few rare instances, adding “-‘s” makes a word plural.

Apostrophes are used to indicate plurals of letters (e.g., “How many s’s are in the word Mississippi?”) and of words when the word itself is the noun (e.g., “A chorus of hello’s greeted the teacher.”). As we’ll discuss in just a moment, apostrophes also indicate pluralization for acronyms that have internal periods (e.g., “My task was to remove all the Mr.’s before the guests’ names.”).

This Rule for Pluralizing Acronyms Is Almost Always True

Almost all acronyms are made plural by simply adding “-s.”

• ID —> IDs
• CD —> CDs
• VP —> VPs
• PhD —> PhDs
• CEO —> CEOs

Abbreviations that end in a period, like “Ed.” (editor) and “vol.” (volume) should have an “-s” added BEFORE the period:

• vol. —> vols.
• Ed. —> Eds.
• sec. —> secs.
• yr. —> yrs.
• hr. —> hrs.

The TWO Exceptions

Exception #1: Acronyms with Internal Periods

If you happen to have an acronym with periods between the letters, you should add “-‘s” (with the apostrophe) to pluralize the acronym.

Most of the time, acronyms do NOT require internal periods. However, a publisher’s style guide may call for certain initialisms to carry internal periods, so it’s important to know how to pluralize those, just in case.

She has two M.A.‘s.

Sometimes it’s better to spell out the abbreviation in order to avoid the abnormal pluralization. Think about your audience and their level of understanding when making this choice.

Another option: She has two master’s degrees.

We consulted with several M.B.A.‘s from the nearby business school before making a final decision.

Exception #2: Irregular Plural Acronyms

Some acronyms are irregular in the plural form, and there’s not a great reason why this happens. You really just have to memorize these.

One example of an irregular plural acronym is MS (as in “manuscript), which is MSS in the plural form. Some other examples include p. (“page”) to pp. (“pages”) and n. (“note”) and nn. (“notes”).

2 Extra Rules About Measurement Abbreviations

Most abbreviated units of measurement are spelled the same in the singular and plural, meaning you don’t need to add anything to make them plural (note that the words are PRONOUNCED in the plural—”10 yards,” not “10 yard”—but the “s” is not required when writing the measurement):

• I needed 10 yd. of fabric.
• Thaw 2 lb. ground beef before beginning this recipe.
• The lot was approximately 8 sq. mi.

If that looks weird to you, remember that you can always spell out the words instead of using the abbreviated versions!

• I needed ten yards of fabric.
• Thaw two pounds of ground beef before beginning this recipe.
• The lot was approximately eight square miles.

When units of measurement are paired with fractions—including those less than 1—the unit is pronounced as if it were plural. It’s still spelled without the extra “-s,” though.

• 0.8 yd. —> “zero point eight yards”
• 1.3 ft. —> “one point three feet”

The singular form is only used when there is exactly ONE.

What questions do you have about pluralizing acronyms? Let me know in the comments and I’ll be sure to find an answer for you!

Click here to find out when acronyms DO and DON’T need internal periods!

Sources:

• Becker, David. “APA Style 6th Edition Blog: Pluralize Numbers and Abbreviations Without Apostrophes.” APA Style Blog (6th Edition Archives), November 21, 2013. https://blog.apastyle.org/apastyle/2013/11/pluralize-numbers-and-abbreviations-without-apostrophes.html.
• The Chicago Manual of Style. 17th ed. Chicago, IL: The University of Chicago Press, 2017.
• Ebbitt, D. R., and W. R. Ebbitt. Index to English. 8th ed. New York: Oxford University Press, 1990.
• Einsohn, Amy. The Copyeditor’s Handbook. 3rd ed. Berkeley and Los Angeles, California: Univ of California Pr, 2011.