Apostrophes for the Plurals of Abbreviations and Awkward Plurals

Apostrophes to Show the Plurals of Abbreviations and Awkward Plurals

Sometimes, a plural is so awkward, it is permissible to use an apostrophe to assist your readers. For example:
  • There are two a's in accommodation. correct tick
  • Your 2's look like your 7's. correct tick
The first thing to make clear is that apostrophes are not normally used for forming plurals. In other words, using an apostrophe to form a plural is usually a grammatical mistake. For example:
  • She will not eat banana's. wrong cross
  • Is it true that pearl's melt in vinegar? wrong cross

The Quick Answer

If you have an awkward plural (usually the plural of a letter, a number, or an unusual abbreviation), you can use an apostrophe to assist your readers. For example:
  • Hawaii is spelt with two i's. correct tick
  • She used six and's in one sentence. correct tick

Beware!

This is not a popular practice (even though all the modern grammar references condone it).
apostrophes for the plurals of abbreviations

Assist your Reader

The advantage of using an apostrophe is that the abbreviation, letter, or number is instantly recognizable. However, when an apostrophe is used to show a plural, it could lead to ambiguity because apostrophes are mostly used to show possession (e.g., the dog's bone) or in contractions (e.g., the dog's eaten the bone). Look at these examples:
  • MP's Plan Failure wrong cross
  • (This newspaper heading is ambiguous. We cannot be sure if the apostrophe shows a plural (the journalist's intent) or possession. Is this title about (1) MPs planning to fail? or (2) the failure of an MP's plan? It's unclear.)
  • The MP's leaving are to be replaced by Monday. wrong cross
  • (In this example, the apostrophe shows a plural. This is likely to cause a reading stutter. Upon reading the sentence, most readers would see "MP's" as a possessive, and some would see it as a contraction of "MP is." Only when readers reached "are" would they realize it was a plural. Of course, the apostrophes in both of these examples are unjustified because "MPs" is not an awkward plural.)
So, remember that using 's to show a plural can lead to ambiguity. Even if there is no real ambiguity, it will at least make the reader pause momentarily to check whether the apostrophe shows a plural, a possessive noun, or even a contraction. In other words, your plural apostrophe is likely to cause a reading stutter.

You should only use an apostrophe in the plural of an abbreviation, a letter, or a number to assist your reader.

Examples of Apostrophes Showing Plurals

Here are some acceptable examples featuring apostrophes for plurals.
  • You use too many and's in your writing. correct tick
  • (The apostrophe assists the reader in this example.)
  • There are two consecutive i's in the words skiing and taxiing. correct tick
  • (The apostrophe assists the reader in this example.)

Apostrophes in Plurals for Uppercase-Only Titles

When writing titles, you are sometimes compelled to use just capital letters. This makes it difficult to show a plural of an otherwise normal-looking abbreviation. Remember that if it assists your reader, you can use an apostrophe to show a plural. For example:
  • CD'S ARE OBSOLETE correct tick
  • TWO LRS'S PER PROCESSOR correct tick

Apostrophes for the Plurals of Awkward Abbreviations

So far, we have seen apostrophes used with awkward plurals (e.g., and's, i's, 6's) and capital-letter-only abbreviations (e.g., CD'S, CCJ'S) but not awkward abbreviations. "Awkward" abbreviations are those that end with the letter S. For example:
  • There are three SUS's in the cell. correct tick
  • (SUS = Soldier Under Sentence)
    (If, as the author, you deem SUS's to be clearer than SUSs, then you can use an apostrophe to show the plural. However, we judge that the disdain for this practice is so strong, you should opt for SUSs.)
  • There are three SUSs in the cell. correct tick
  • (This does look a little awkward, but we judge it better than SUS's. If you disagree when it comes to your plural abbreviation, then you can use an apostrophe.)

Do not Use an Apostrophe for the Plural of a Normal Abbreviation

It is worth reiterating this point. Do not use apostrophes for the plurals of normal abbreviations. For example:
  • He had 4 CCJ's against him. wrong cross
  • He had 4 CCJs against him. correct tick
  • (CCJ = County Court Judgment)
  • M.O.T.'s wrong cross
  • M.O.T.s correct tick
  • (MOT = Ministry of Transport / also Ministry of Transport test)
  • MOT's wrong cross
  • MOTs correct tick
(NB: It is often the writer's choice whether to use periods (full stops) in abbreviations.)

Do Not Try Too Hard to Avoid the Apostrophe

Of course, there are other ways to show an awkward plural. For example:
  • Hawaii is spelt with two "i"s. correct tick
  • Hawaii is spelt with two Is. correct tick
  • She used six ANDs in one sentence. correct tick
  • She used six ands in one sentence. correct tick
These methods are acceptable, but the apostrophe version is usually far neater and clearer.

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This page was written by Craig Shrives.