The Apostrophe: Beyond the Basics

by Erin Brenner on August 26, 2010

In “Punctuation Points: Possessing the Apostrophe,” I outlined the three main uses for the apostrophe:

  • It shows possession for a noun.
  • It shows the omission of some letters in a word or numbers in a year.
  • It shows plurality of single letters, single numbers, and abbreviations.

We discussed the different cases of using the apostrophe for plural and singular nouns and why pronouns are an exception. Today, I’ll review the remaining rules for using the apostrophe to show possession, as well as the rules for showing omission and plurality.

More Cases for Using the Possessive Apostrophe

  • Double possessive (or double genitive): In some cases, use of and apostrophe in same phrase.

    a cousin of Mary’s
    a sister of mine

    The double possessive is sometimes seen as a mistake, but it isn’t. The usage dates back to Middle English and has become idiomatic.

  • Joint possessive: Use the apostrophe on the last item in a series of elements when the elements own something together.

    Bill and Erin’s car (they share one car)
    Bill, Dave, and Tim’s father-in-law (they have the same father-in-law)
    Bill’s and Erin’s cars (they each have a car)

  • Possessives of possessive names: If the name of a company or other thing is already a possessive, you do not need to add another apostrophe s. You can either recast the sentence or use the original possessive name.

    Sean and Duncan love going to Friendly’s. Friendly’s ice cream is the best, they say.
    OR
    Sean and Duncan love going to Friendly’s. The ice cream at Friendly’s is the best, they say.

  • Possessives of inanimate objects: Despite rumors to the contrary, an inanimate object can form a possessive.

    The car’s engine is overheating.
    The laptop’s hard drive is fried.

  • Set phrases: A couple of set phrases take an apostrophe s in an idiomatic way.

    father-in-law’s truck, not father’s-in-law truck
    anyone else’s room, not anyone’s else room (same holds true for other else phrases)

  • Units of measurement: The unit gets an apostrophe when it modifies a noun.

    15 years’ experience
    two weeks’ notice
    5 yards’ worth of material

    Note, however, that the phrase 7 months pregnant and the like do not take the apostrophe. In this case, pregnant is an adjective, not a noun, and the phrase means being pregnant for the stated time (e.g., 7 months).

Whew! Now that we have the massive possessive apostrophe out of the way, let’s quickly run through the two other apostrophe rules.

The Omission Apostrophe

The apostrophe is also used to make contractions:

The ’80s (this one is an omission, not a contraction)
don’t
shouldn’t
po’ boy

The Plurals Apostrophe

Finally, the apostrophe is sometimes used to make single letters, single numbers, and abbreviations plural:

Sean got all A’s on his report card.
Disco was popular in the 1970’s.
The CEO’s are meeting after the VP’s.

Whether you use the apostrophe to form plurals in these cases depends on your style guide. Here are some of the popular ones:

  • CMS (16th ed.): For capital letters, numerals, and abbreviations, add s; for lowercase letters, add apostrophe s (7.14).
  • AP (2010): For numerals, abbreviations, and multiple letters (e.g., VIP), add s; for single letters, add apostrophe s (“plurals”).
  • APA (6th ed.): For single letters, numbers, and abbreviations, add s (except for p.; its plural is pp.).
  • NYT Manual of Style (2002): Use apostrophe s to form plurals of single letters, single numbers, and abbreviations.
  • Yahoo: For single letters numbers, and abbreviations, add s, unless the result would be confusing. In which case, use apostrophe s.

But you should never form a plural noun with an apostrophe s:

Wrong: The car’s are on the track.
Right: The cars are on the track.

That’s it. Did I answer all your questions on the apostrophe? If not, put your concerns in the comments below and I’ll try to answer them.

Update: Thanks to Danny Marcus for pointing out errors in this post.

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