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Possessive with acronyms ending in S

How do you properly punctuate an acronym such as ACS when you want to show possession? Is it ACS’s or ACS’?

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Nicole, it works like this:

You make the plural and the possessive in the usual way for acronyms. For example: I had a VCR. The VCR's power button was broken. I bought another VCR, so I had two VCRs. Then the second one's channel selector button broke, so I could tell that the VCRs' buttons were made cheaply.

This rule is exactly the same when the acronym in question ends in an S. So you have one ACS, and a thing belonging to it is the ACS's thing. Or you have additional ACSs, and something belonging to the ACSs is the ACSs' thing.

Got that? :)

speedwell2 January 20, 2005, 3:45pm

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Maybe not. I confess I explained badly, so after some consideration I'll take the liberty of making up something ACS could stand for (since you did not specify).

OK, let's pretend I'm a passionate fan of the (purely theoretical) hottie Scottish movie star Alexander Cameron, and I start a fan club, the Alex Cameron Society (ACS), here in Houston. The Alex Cameron Society's (ACS's) members wear a pin made from a scrap of the Cameron tartan and a gold star.

I find out that another girl started an Alex Cameron Society (ACS) in Los Angeles last month. So now there are two different Alex Cameron Societies (ACSs) in the United States.

I got in touch with the other girl, and we decided to pool our Cameron movie collections so that any member of either ACS could enjoy them. Now there are a dozen movies in the Alex Cameron Societies' (ACSs') merged collection.

Anonymous January 20, 2005, 4:04pm

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Just an FYI: ACS and VCR are initialisms, not acronyms. According to most dictionaries, an acronym is a pronounceable word formed from the initials of a multi-word name. A couple of examples are SCUBA, which stands for Self-Contained Underwater Breathing Apparatus, and AIDS, which stands for Acquired Immune Deficiency Syndrome.

Cole March 3, 2005, 12:04pm

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Except that would mean they can't be called TLAs.

Persephone Imytholin March 3, 2005, 8:43pm

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"Initialisms are made up of the initial letters of words and are pronounced as separate letters: CIA (or C.I.A.), NYC, pm (or p.m.), US (or U.S.). Practice varies with regard to periods, with current usage increasingly in favor of omitting them, especially when the initialism consists entirely of capital letters. Acronyms are initialisms that have become words in their own right, and are pronounced as words rather than as a series of letters, for example, AIDS, laser, scuba, UNESCO. In many cases the acronym becomes the standard term and the full form is only used in explanatory contexts."

--Microsoft Encarta Reference Library 2005

The fact that the initialism "TLA" misuses the term "acronym" doesn't mean that its misuse is correct, despite its ironic nature. Cole is right; "acronym" is still defined as a word formed from initials that are pronounced together as one word, and "initialism" is defined as an abbreviation formed from initials that are all pronounced separately.

lamont2718 March 3, 2005, 10:51pm

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Always use the lower case for the possesive and the plural at the end of initials, acronyms and numbers.
Please remember to use the apostrophe at the beginning of a contracted date.

e.g. In the '70s, ACS's profits were down. I think I will count my CDs.

Gerry Merchant March 8, 2005, 2:28pm

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Except......TLA doesn't stand for Three Letter Acronym. It stands for Three Letter Abbreviation, which is correct. I'm not sure when the misuse began, but I have heard this term misued in formal settings.

John May 20, 2005, 2:50pm

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Please tell the difference between abbreviation,acronym and initials.

mallikaj August 22, 2006, 3:23am

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OK-several months later..... :-0

What if the last word in an initialism for a government agency is a plural word? Do you add an apostrophe only or an 's? For instance, the Centers for Medicare and Medicaid Services initialism is 'CMS.' To show possession while using the initialism, is it proper to use CMS' or CMS's?

jnn41wms February 27, 2007, 10:15am

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I don't know if this is really definitive or relevant, but consider that the S in CMS represents the first S in Services, not the pluralizing s at the end. Would that suggest that -'s is the proper ending?

porsche February 28, 2007, 7:45am

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Dear Grammar Stars,
What is the proper possesive for for the abbreviation Jr.?
Would it be Jr.'s?
I'm having a hard time finding the proper answer.
Jim V.

jimv3 May 23, 2008, 4:30pm

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All acronyms are initialisms, but not all initialisms are acronyms. That is why people commonly accept 'acronym' and tend to not even know what 'initialism' means. It's kind of the way everyone calls all forms of raw Japanese food 'sushi', even though sushi is really only the American invention of rolls. The other popular forms that we see are 'ngiri' and 'sashimi', and the three terms are not interchangeable (except among the uninformed).

TLA = Three-Letter Abbreviation/Acronym (my point being that it should be hyphenated; I'm not arguing the definition of the 'A').

The proper possesive form of 'Jr.' is Jr.'s. ('Sr.', therefore, becomes Sr.'s.)

paulmuirhead9 August 4, 2010, 2:36pm

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Our animal shelter LARAS' House??? or LARAS House is an acronym for
Limestone Animal Rescue & Adoption Shelter. There is a debate among the board as to how this should read. We are trying to put up a sign and I want to do it properly but have not clue. One board member says we should use the apostrophe because it is possessive, the other says it is not necessary because it is an acronym...please help, we need the sign. Thanks Peggy W.

Peggy Wilson April 17, 2011, 6:49am

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@Peggy Wilson: You're treating that initialism (acronym) as a name, but while this is cute, it's really not correct. Therefore, your example should very clearly be the "LARAS House" (note the prefixing "the", as well). If it was a "…Facility", it would be the "LARAF House".

And, back on the original topic: The only time an apostrophe should be used before an "s" to indicate plurality, would be if the result could be otherwise misconstrued.

A (poor) example: If I'm trying to indicate the plural of the ninth letter of the alphabet, I cannot simply indicate "is", since this would be confused with the 3rd-person singular present form of "be". Therefore: "The sign kit included several dozen lower-case tiles, six of which were i's"

But, again, this is an exception. Apostrophes are used to indicate possession; simply adding an "s" is the primary method of indicating plurality.

Mr. Pedantic January 14, 2013, 1:39am

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Actually, the original function of the apostrophe was to show a missing vowel, a use we still see today in contractions - 'I'm, he's, she'd' etc. As far as I understand, the reason that it is used for possessives is because it signals a missing e which used to be in the Old English genitive form, which ended in -es.

Warsaw Will January 15, 2013, 2:21pm

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paulmuirhead9, good example, but you're description of sushi is a bit off. Sushi refers to the rice that accompanies the fish, not the fish itself. Sashimi is not a form of sushi, it's sashimi. The California roll was created in the U.S., but the technique of rolling is very much Japanese.

Dangle June 24, 2013, 10:34am

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I disagree with John (from 8 years ago!). I don't know his authority on the original coinage of TLA, but it stands to reason that the A was not intended to stand for "abbreviation," as an abbreviation is primarily a shortened form of a single word (or phrase), and not what would be considered a "TLA" by most users of the term.

[Just as all acronyms are initialisms, but not all initialisms are acronyms, all acronyms and initialisms are abbreviations, but not all abbreviations are either acronyms or initialisms]

There would have been no reason to coin the term TLA for "Ala." or "Inc.", for example, as these are not fundamentally different from 2-letter or 4-letter abbreviations (e.g., Mass. and Co.). I think the coinage of "TLA" was a response to a preponderance of 3-word expressions (hence, 3-letter initialisms) in the decades of the 70's and 80's, perhaps particularly in the computer realm. "CPU," "GUI," "DOS," "RAM," for example. My guess is that the use of "A" for "acronym" was just a more recognizable word to most people than "I" for "initialism" would have been (my spell check doesn't recognize it, for example). And most people appreciate the humorous irony of "TLA" being a TLA, even if it is not strictly accurate, in either sense.

SinTax'ed Enough June 26, 2013, 12:18am

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So with regard to acronyms/initialisms ending in 's', and assuming that " 's " is correct for the end of the word, if the initialism actually ends in an 'S', is there a rule for whether this should be written as " 's " or just " ' " - for proper nouns ending in 's', an apostrophe by itself is generally considered correct - e.g. James'

Apot August 22, 2013, 7:37am

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There is a lot of knowledge here, but no one seems to have answered porsches' question (although somewhat restated by Apot). If the last letter of the initialism is "S" and stands for a plural such as "services," does one show possession following the initialism with a single apostrophe or apostrophe S?

Proper Usage September 30, 2013, 8:16pm

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@Proper Usage - well, specifically in answer to porsche's question, here are a couple of examples:

1. AWS - Amazon Web Services. In a book called Electric Beanstalk, they explain that this is 'one of Amazon AWS's services'. They then use AWS's four times in the book, although they seem to avoid it on their own website (

2. AHS - Alberta Health Services - In an editorial, the Calgary Herald write 'AHS’s new benchmarks must improve reporting, not obscure it'

3. IMLS - Institute of Museum and Library Services - on their own website they invite people to 'Submit Your Ideas on IMLS's Strategic Plan'

These were the only organisations I could find in the first five pages or so of Google which both had Services in the name and used initialisms.

Warsaw Will October 1, 2013, 12:18pm

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IRS's, BCS's, CBS's, and probably dozens more. But I think I may have relaxed the definition of what you were looking for, Willie from Warsaw.

Harry Boscoe December 17, 2013, 6:23pm

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@Harry Boscoe - As far as I know, your examples all refer to singular nouns - Inland Revenue Service, Columbia Broadcasting System etc, which certainly answer nicolejamison's original question, and where I don't think there's much debate.

But I was specifically trying to find examples that would answer porsche's question about what happened when the last word of the initialism was a plural, eg Services.

Warsaw Will December 18, 2013, 2:51am

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Two really good examples - cuz they come from *huge* government bureaucracies, which wouldn't *allow* bad punctuation - are the CMS, Centers for Medicare and Medicaid Services (mentioned above, I think), and its "parent" organization, the HHS, Health and Human Services. Both of these, in their press releases, use the 's construction: "CMS's" and "HHS's". But maybe that counts as only *one* example, because I suspect the same people may be the copy editors at those two places, or they learned everything they know from each other.

Harry Boscoe December 21, 2013, 5:59pm

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And then there's also the OAS - the Organization of American States. Many many writers use "OAS's" as the possessive of that organization's initialism-with-an-s-ending-and-plural-third-word.

Harry Boscoe December 21, 2013, 6:05pm

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@Harry Boscoe - now you're talking. Here are some non-governmental sources for your examples:

Inside the OAS's Cuba Conundrum - Time Magazine
HHS's Sebelius: 'No, My Halloween Costume Is Not A Pinata' - Forbes Magazine
Can Physicians Cope With CMS’S Requirements? - PVW Health Care Law Blog

And a few others, for good measure:

A history of HUS: HDS's file-development hustle - The Register (Hitachi Data Systems)
CDS's parent company - CDS website (Clearing and Depository Services Inc, Canada)
Three elected to serve on ASTC’s Board of Directors - ASTC website (Association of Science-Technology Centers)

So between us I think we have definitively answered porsche's question.

Warsaw Will December 22, 2013, 6:51am

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@jnn41wms, the press releases from the Centers for Medicare and Medicaid Services usually add 's to their acronym's possessive form. However, in some other cases, I've seen how they simply add the apostrophe. The text below was extracted from their press release published on 07/27/2015, Clarifying Questions and Answers Related to the July 6, 2015 CMS/AMA Joint Announcement and Guidance Regarding ICD-10 Flexibilities:

"No. As stated in the CMS’ Guidance, for 12 months after ICD-10 implementation, Medicare
review contractors will not deny physician or other practitioner claims billed under the Part B
physician fee schedule through either automated medical review..."

Donovan July 28, 2015, 8:19am

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Just for the record:-

Acronym: An abbreviation formed from the initial letters of other words and pronounced as a word (e.g. ASCII, NASA, LASER RADAR).

Initialism: An abbreviation consisting of initial letters pronounced separately (e.g. BBC, CIA, IBM).

Hairy Scot July 30, 2015, 11:54pm

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How does one write the possessive form of initials ending in S and also using periods, as in C.I.S.? C.I.S.'s?

carolyn1 February 26, 2016, 11:52am

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So here is my question. We are using acronyms that end is "s" How do you show them as many?

ex: Welding Procedure Specification (WPS)
Do you write WPSs, leave at WPS (can be singular or multiple), or WPS' ?

Tammi Nervig April 8, 2016, 12:04pm

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Does no one see the irony in the fact that this site offers professional proofreading services, yet they misspell the word acronym in 2 different ways? (acromym in the title and acromyn in the subtitle)

Scott Jenkins June 6, 2016, 8:54am

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What's the right way to punctuate a plural possessive of an acronym? For instance, if you have more than one PDF, do you write "PDF's size," or "PDFs' size," or "PDFs's size"?

Akshata October 23, 2016, 5:52pm

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An acronym is a pronounceable word made up of a series of initial letters or parts of words the possessive, or the plural possessive is handled in exactly the same way as it is for all words which end in S.
I would assume that the same hold true for the possessive plural of a set of initials.
eg: RADARs range, PDFs' size

Hairy Scot October 23, 2016, 6:17pm

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Yes     No