My understanding of the correct use of the apostrophe would be:

  • the posessive form, e.g. ApostropheLover's obsession with the apostrophe
  • a contraction: don't, it's, there's
  • an abbreviation, my id' badge is in my backpack

Is the third case correct? How should one punctuate an abbreviated word like "id" (identification) or "repo'" (repository)?

  • 1
    There are numerous earlier answers to this sort of question. If you read them you will find strong opinions, and in general no consensus in this highly contentious area. But even given that, your third example is the first time I have seen that usage.
    – JeremyC
    Commented Mar 13, 2018 at 9:57
  • Interesting. So also "repo." or "id." might be more common than the apostrophe use?
    – Alex
    Commented Mar 13, 2018 at 10:09

2 Answers 2


ID badge is a compound noun: ID + badge.

You can use the word "ID" on its own.

You could write:

"The ID's front side shows a name, a date of birth, and a nationality."

  • Why do you capitalise "id"?
    – Alex
    Commented Mar 13, 2018 at 10:08
  • It's pronounced ID (ay-dee). It stands for Identity Documentation. Otherwise it could be confused with "id" which is a Freudian concept.
    – Boondoggle
    Commented Mar 13, 2018 at 10:12
  • I think you mean "eye-dee" for the phonetics; I don't believe this addresses my concern regarding "case 3".
    – Alex
    Commented Mar 13, 2018 at 16:26
  • You're right, I meant eye-dee. No, id' badge is not correct imo.
    – Boondoggle
    Commented Mar 14, 2018 at 7:04
  • ID is now such a common term that those letters on their own require nothing more to signify that they are an abbreviation. But, if you wanted to do so, it would be more usual to use stops:"I.D." For a very long time in UK central government service it has been the practice to omit stops in abbreviations: MPs instead of M.Ps. for Members of Parliament. The reason for omitting stops was that it avoided unnecessary keystrokes by the typist (who back in the 1970s was never the originator of the document).
    – JeremyC
    Commented Mar 14, 2018 at 17:33

No, your example in the third case is incorrect (as already pointed out by Boondoggle).

Instead, consider gov't as an example of its usage for abbreviations.


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