Apostrophes with Acronyms and Abbreviations

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Apostrophes in Plural Acronyms and Abbreviations

It is common to see an apostrophe used in the plural of an abbreviation or an acronym. For example:
  • She had two CJJ's.
  • Buy three CD's for the price of two.
  • Our garage can do twenty MOT's in day.
As the apostrophes in the examples above do not make the text clearer, I am happy to mark them as incorrect. However, despite what some of the more dogmatic grammarians might tell you, it is not always incorrect to show the plural of an abbreviation or an acronym with an apostrophe.

apostrophes after abbreviations and acronyms
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Apostrophes in Unwieldy Plurals

If the writer thinks an apostrophe helps readers, then one can be used in the plural of an abbreviation or an acronym. For example:
  • She sent two SOS's.
  • I have five SUS's in my care.
Warning!


Be aware that using an apostrophe to show the plural of an abbreviation or an acronym is not a popular convention. Lots of your readers will hate it.
As most of your readers would prefer the non-apostrophe versions below, you are advised to set a high threshold for using an apostrophe to show a plural. (In other words, you should try hard to avoid it.)
  • She sent two SOSs.
  • I have five SUSs in my care.
Of course, the two examples above are acceptable, but they do look slightly awkward. Therefore, using an apostrophe to avoid an unwieldy-looking plural has become permissible.

Apostrophes in Uppercase Plural Abbreviations and Acronyms

When only capital letters can be used, it is permissible to use an apostrophe to show the plural of an abbreviation or an acronym. (This happens mostly in document titles or advertisements.)
  • CDS REQUIRES THREE CD'S
    • (The Chief of Defence Staff requires three compact discs.)
  • VISITING SUS'S AFTER 1 APRIL
    • (Visiting Soldiers under Sentence after 1 April)

Apostrophes in Awkward Plurals

Apostrophes can also be used in other awkward plurals. For example:
  • Your 2's look like Z's.
  • You use too many and's in your writing.
  • There are two a's, two c's, and two o's in accommodation.
Of course, there are other ways of writing these to avoid the apostrophes, but using an apostrophe is tidy and efficient.

Read more about apostrophes in plural abbreviations and awkward plurals.
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See Also

Using apostrophes Apostrophes for possession Apostrophe placement rules Apostrophe after s Apostrophe after z Apostrophe before s Apostrophes for awkward plurals Apostrophes in contractions Apostrophes in expressions like 2 years' pay and a day's notice Apostrophes used incorrectly for plurals Apostrophe exercises Apostrophes in names Apostrophe misuse Apostrophes in contractions Using brackets and parentheses Using colons Using commas Using dashes Using hyphens Using quotation marks Using semicolons