The Plurals of Abbreviations and Acronyms
The Quick AnswerThe plural of an abbreviation is formed by adding "s." For example:
- RTA > RTAs (RTA = Road Traffic Accident)
- COS > COS's (COS = Chief of Staff)
- COS > COS'S (An apostrophe is useful when only capital letters are permissible, e.g., in titles.)
Forming Plurals of Abbreviations and AcronymsThe plural of an abbreviation or acronym is usually formed by adding "s" to the end. For example:
- MOT > MOTs
- ATM > ATMs
- Once I have finished this PC, I will only have 3 PCs to configure.
- We have a dozen SUS's to collect from the station. (SUS - Soldier under Sentence)
(In this example, the writer considers SUS's to be clearer than SUSs and has opted to use the "'s" version. This is acceptable. Be aware though that this could irk a fair proportion of your readers. Nevertheless, it is the writer's decision whether to use the apostrophe to aid understanding.)
- The firefighters could not assist with three of the RTAs because the BA's were still in the stores. (RTA - Road Traffic Accident / BA - Breathing Apparatus)
(There is no good reason to write BA's - especially after showing how abbreviations are pluralized with RTAs; i.e., it's also inconsistent.)
Pluralizing Abbreviations with Periods () / Full Stops ()The rule above applies to abbreviations with periods / full stops too. For example:
- Once I have finished this P.C., I will only have 3 P.C.s to configure.
- Not one of the S.O.S.'s was received by the coastguard.
This garage sign in the UK should say M.O.T.s not M.O.Ts.
Here is another example:
- Anna was refused credit due to three C.C.J.s. and mortgage arrears. (CCJ - County Court Judgment)
- We have only done two M.O.T.s since January.
Avoid the Version with an ApostropheAs covered in this lesson on apostrophes, "'s" can be used to show possession. For example:
- The MP's photo shoot will be held at 7 o'clock. (This is the photo shoot of one MP.)
In summary, you should be aware that the "'s" version is an option you can employ to assist the reader in spotting an unwieldy abbreviation instantly. However, in all other cases, you should opt for the "s" version.