For abbreviations - both acronyms and initialisms - where the last word in the abbreviation is the noun, I'm accustomed to adding an 's' with no apostrophe (e.g. ATMs), as described in the answer to this question: What is the correct way to pluralize an acronym?

But how do you pluralize abbreviations where the noun is not the last word? E.g. 'Point of Presence' (POP)

I can see how 'POPs' could read 'Point of Presences', when the intention is 'Points of Presence.'


Virtually always, the s follows the full abbreviation even when a word other than the last one is the proper plural. Paul Brians in Common Errors in English Usage cites


This style is also recommended in the AP Style Guide, so it is what you will see in most newspapers. But not all.

The other option is to discard the s altogether, as in this news story from the Cleveland-area News-Herald:

Byrd had five home runs and 19 RBI in 34 games.

This is certainly not a typo. Many commentators prefer this, but it is simply that, a preference. As a former editor at ESPN, I had this discussion many times with writers and other editors, many insisting that there is only one right way to do it. Clearly, that is not true. If you prefer the s, use it, but only after the entire abbreviation. Nobody, but nobody, uses RsBI.

  • OK, I've fixed, but I haven't mentioned Schudel because the decision to include an "s" or not would not be his decision--it would be the editor's. – user66965 Jun 24 '16 at 2:56
  • As far as I know, no one uses MspH or MPHs for miles per hour, which suggests that there is a degree of fluidity in the way people apply the "add an s at the end" rule or the "don't add an s at the end" rule in dealing with initialisms. One important variable, I suspect, is whether the initialism is capped or lowercase: plural rpm or mph seems much clearer to me than plural rpms or mphs. But you are certainly correct that people never place the plural after the initial of the word that is plural in its whole-word form. – Sven Yargs Aug 9 '16 at 3:04
  • @SvenYargs - rpm and mph are different, in that the initialisation is based on the plural noun, rather than a single-noun-based initialisation being pluralised. – AndyT Aug 9 '16 at 16:12
  • @SvenYargs These are considered measurement units. There is an infinity possible decimal values for each unit, and there is only a single case where it is singular - this makes it implicitly plural. Another reason is that adding unnecessary 's' can change the unit - if 'meters' is abbreviated to 'ms', it becomes 'milliseconds'. – Jai Sep 27 '17 at 2:51

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.