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What is a Possessive Noun: The Rules Every College Student Needs to Know

There’s an adage that says possession is nine-tenths of the law. Another, less memorable truth might be this: possession accounts for nine-tenths of grammatical errors.

Okay, maybe not nine-tenths. However, the rules for forming possessive nouns in English are tricky enough to trip up even professional writers. And while an errant apostrophe or extra “s”added to your plural possessive nouns might go unnoticed by nine-tenths of the public, they won’t escape the eyes of your professors.

So what are the rules? How can you tell the difference between possessives and plurals? What about when a word is possessive and plural? When do you use an apostrophe or an apostrophe + “s”? These are the questions that turn quick assignments into hours-long sessions of self-doubt. But it doesn’t have to be this way.

Keep reading to learn these rules once and for all, then test your knowledge with our possessive nouns worksheets. If you’re still stuck, our spell check is always here to help you assuage doubt so you can reclaim your time from the clutches of academic anxiety.

What are Possessive Nouns?

A possessive noun is a noun that shows possession or belonging:

  • Mary’s dog
  • The girls’ jackets

Plurals are often confused with possessives, but they are not the same thing. Here are a few plural examples:

  • Seven trees
  • Fifty dancing dogs

When you’re unsure if a word is a plural, possessive, or both, try reversing the words and adding the preposition “of”:

  • Original: Mary’s dog
  • Reversed: Dog of Mary

While you’re unlikely to refer to a dog in this way, doing so would not change your meaning.

  • Fifty dancing dogs
  • Fifty dogs of dancing

With this phrase, you have a new and remarkably unclear meaning. There’s no possession here; these dancing dogs are plural.

Once you can separate possessive nouns from plurals, you’re ready to move on to demonstrating possession. If you’re looking to learn about the syntax and semantics of possession, read this entry to get more info.

Singular Possessive Nouns

The apostrophe is a cruel mistress when she’s not given proper care. Allow her someplace she doesn’t belong and embarrassment will shortly follow. So where does she belong? Check out this useful link about her myriad uses, and keep reading for her proper use with singular possessive nouns.

In the last section, you learned to answer the question: What is a possessive noun? In this section, you’ll focus on singular possessive nouns. First, however, you need to sharpen your eye to find words that truly are singular. Here’s a trick you can put into quick use: insert the word one before the word in question:


  • Adding one to the word girl gives you one girl, which is grammatically correct and confirms that girl is singular.


  • Adding one to the word mice gives you one mice. Even though mice doesn’t end in s, it is plural, as is evidenced by the grammatically incorrect one mice.

Possession Rules

After identifying the singular words, demonstrate possession by applying one of these rules. If a word is:

Singular and doesn’t end in s, add ‘s.

  • Mary’s dog
  • the library’s hours

Singular and ends in s, add ‘s (with some exceptions).

  • Agnes’s brother
  • the octopus’s tentacles

Singular and ends in s but pronunciation would suffer from ‘s, add only .

  • Socrates’ writing
  • Moses’ robe

Your ear will help you determine if pronunciation will suffer; the sound made by an s is called a sibilant, and your ear knows how to treat it. For example, in this sentence:

  • Wes’s bicycle was his pride and joy.

The singular Wes shows possession with ‘s. However, it doesn’t work with Socrates instead of Wes:

  • Socrates’s bicycle was his pride and joy.

You can tell it’s wrong because your ear tells you it’s wrong. Try it another way:

  • Socrates’ bicycle was his pride and joy.

This is the correct way to show the relationship between Socrates and his bicycle, and your ear agrees with the words on the page to confirm it. That agreement might even cause you to overlook the other glaring error in that sentence: the bicycle was invented in 1817, over 1,400 years after Socrates’ death.

Any rule with exceptions is a rule worth confirming with your style guide. MLA format, for example, uses ‘s in instances where the AP Stylebook uses only an apostrophe. Our citation services can help you with these and more styles.

Plural Possessive Nouns

There’s an atrocity of the written word tucked away in gardens and hanging proudly on front doors all across America. Examples of plural possessive nouns lovingly painted in elegant script on pallet-wood signs. And they’re all wrong:

  • The Smith’s

The Smiths have omitted a word or abused an apostrophe; they’ve confused the plural for the possessive. You can avoid this mistake by recalling the rules that define a possessive noun. This is the step that the Smiths skipped.

A possessive noun has possession of something. The Smiths is plural, representing more than one member of the Smith family. For plurals that end in s, an apostrophe after the final s shows possession:

  • The Smiths’ house
  • The dogs’ love of dancing

You’ll notice above that the word house follows the Smiths’House is the thing to which the Smiths are claiming possession. They might also opt just to drop the apostrophe and the possession with The Smiths.

Clan Smith may eliminate the need for a whimsical sign altogether by answering their door and introducing themselves to guests on a case-by-case basis. Your move, Smith family.

Not all plurals end in s. Consider these examples of plural possessive nouns:

  • the women’s hammers
  • The People’s Court

Plurals that end in a letter other than s show possession with an ‘s.

Joint Possession and Other Scenarios

In instances of shared possession, the last word in the sequence becomes the possessive noun and demonstrates possession for the previous items in the series.


  • Walter and Jesse’s lab

Walter and Jesse share the lab equally. Jesse, coming last in the sequence of names, is given an ‘s which demonstrates possession for both he and Walter.

Treat two nouns possessing something different as two separate possessive nouns:


  • Walter’s and Jesse’s arrest warrants.

While Walter and Jesse are both wanted by the police, separate arrest warrants exist. They are each given an ‘s to show possession of their warrants. While this can seem tricky, you can always work through it by answering the question: what is a possessive noun? Starting here will help you identify what you need to show possession of and who or what possesses it.

When one noun modifies another, in most instances, drop the apostrophe:


  • teachers union

Practices vary by style guide for this situation.

Very rarely, an apostrophe is used to make a plural. When writing about individual letters or numbers, an apostrophe may be appropriate to create the plural:


  • Dot your i’s and cross your t’s.

Abbreviations may also be made plural with an apostrophe:


  • M.D.’s
  • P.h.D.’s

Of course, your style guide will be the starting point for these choices. Neither the periods nor the apostrophes in the above example would be appropriate in APA format, which instead uses MDs and PhDs.

Possessive Nouns Worksheets

Test your knowledge with these questions and problems using the information you learned in this guide. After you’re done, scroll down for the answer key:

  1. What is a possessive noun?
    • A) Any noun that ends in s or es
    • B) Any word that contains an apostrophe
    • C) A noun that shows possession over something

In questions 2-5, choose the correct format for the possessive nouns:

2. The store only sells (mens clothing / men’s clothing).

3. For (heaven’s sake / heavens sake), the Smith family bought another garden sign.

4. The (books pages / book’s pages) were numbered incorrectly.

5. I won’t retweet any of (Molly’s tweets / Mollys tweets) again until she admits to subtweeting me.

For questions 6-10, modify each sentence so it contains plural possessive nouns:

6. These feathered hats belong to those ten musicians.

7. The branches of ten trees were damaged by a storm.

8. Mary and Natasha are roommates who have a pet cat.

9. Mary and Natasha are roommates, each with her own pet cat.

10. Socrates hated his sandals because they frequently caught on his robes.


How did you do? Scroll below for the answers.


Answer Key:

  1. C
  2. men’s clothing
  3. heaven’s sake
  4. book’s pages
  5. Molly’s tweets
  6. These are the ten musicians’ feathered hats.
  7. The ten trees’ branches were damaged by the storm.
  8. This is Louisa May Alcat, Mary and Natasha’s cat.
  9. Mary’s and Natasha’s cats are suspicious of strangers.
  10. Socrates’ sandals caused several embarrassing robe mishaps.

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