What is an Apostrophe? Definition, Rules for Apostrophes

Apostrophe definition: An apostrophe is a punctuation mark used to show possession or to show the omission of letters.

What is an Apostrophe?

An apostrophe is a type of punctuation mark. It is used to show when one noun possesses another noun.

Examples of Apostrophes Showing Possession

Here are a few examples using apostrophes.

  • Sarah’s book
  • the child’s toy
  • the men’s room
  • Sandy’s car

In the first example, the book belongs to Sarah. She may have purchased it herself or received it as a gift, but it belongs to her.

For the literary term apostrophe, see here.

Examples of Apostrophes Indicating Omission of Letters

possessive apostrophe after s The apostrophe is also used as a mark to show when letters are omitted from words.

  • can’t
  • ‘tis
  • won’t
  • shouldn’t
    • Cousins wasn’t at his best Sunday, but he shouldn’t be blamed for all of those offensive shortcomings. –The Washington Post

In all of these examples, a letter is omitted where the apostrophe stands.

  • can’t > cannot
  • ‘tis > it is
  • won’t > will not
  • shouldn’t > should not

Rules for Using Apostrophes

The above section outlines the general uses of the apostrophe. There are, however, specific rules for apostrophes that must be followed to be grammatical correct.

Apostrophe Rules for Possessive Nouns

Here are the rules for forming singular possessive and plural possessive nouns as well as a few other examples.

Rules for forming possessives:

  • apostrophe usage For all singular nouns
    • add apostrophe “s” to the end
    • Examples:
      • Sean’s book
      • Charles’s pet
      • dog’s bed
  • For plural nouns not ending in “s”
    • add apostrophe “s” to the end
    • Examples:
      • children’s room
      • people’s choice
      • group’s decision
  • For plural nouns ending in “s”
    • add apostrophe after “s” to end of word
    • Examples:
      • cats’ bowl
      • students’ room
      • kids’ pool
  • possessive apostropheFor compound words
    • add apostrophe “s” to the end of word
    • Examples:
      • mother-in-law’s cooking
      • stock market’s fluctuation
      • national monument’s tower
  • For joint possession
    • add apostrophe “s” the end of last word
    • Examples:
      • Martin and Luisa’s cousin
      • Mom and Dad’s response
      • James, Mark, and John’s assignment
  • For possession showing time
    • add apostrophe “s” the end of last word
    • Examples:
      • That was all in a day’s work.
      • We will be there in an hour’s time.

Apostrophe Rules for Omission of Letters

s or s In contractions, apostrophes are used to show that letters are missing from a word.

  • The apostrophe is placed where the letters are omitted.
  • Examples
    • cannot
      • can’t
    • do not
      • don’t
    • should not
      • shouldn’t
    • it is
      • ‘tis
    • it is
      • it’s
    • would not
      • wouldn’t
    • will not
      • won’t

Apostrophe Rules for Awkward Plurals

when to use s Writing can become confusing and awkward when trying to make lower-case letters plural.

For example, if I want to say that a word has more than one of the same letter.

  • Aaron contains two a’s.

Consequently, using an apostrophe for lower-case plurals can help resolve some of this confusion.

  • Add apostrophe and “s” after the letter.
  • Examples
    • This word has two a’s.
    • There are two l’s in llama.

Do Not Use Apostrophes with These Pronouns

correct grammar apostropheThere are some pronouns with which you will never use apostrophes because they have specific forms to indicate possession.

Personal Pronouns

Relative Pronouns

  • Do not use apostrophes with relative pronouns.
  • Never say:
    • which’s paper
    • who’s television (this means: who is television)
      • say: whose television

Not All Words Ending in “S” Need an Apostrophe

apostrophe possessionThe important thing you should note is that not all words ending in “s” need an apostrophe. Many words ending in “s” are simply plural words.

The only words that should ever show possession with an “apostrophe s” are nouns that show possession.

Verbs, adjectives, adverbs, and other parts of speech should not be made possessive. That is, they should not have an apostrophe followed by an “s.”

An apostrophe and an “s” should only be added to nouns to show appropriate possession.

For example,

  • Incorrect: The student’s wanted to go on a field trip.
    • The students are not possessing anything in this sentence. Rather, this sentence is referring to the plural student.
  • Correct: The students wanted to go on a field trip.

Summary: What are Apostrophes?

Define apostrophe: the definition of apostrophe is the mark that indicates the possessive case or the omission of letters.

In summary, an apostrophe is:

  • a punctuation mark
  • used to show when a noun possesses another noun
  • used to show omission of letters