Understanding the Suffix S: Grammar Rules and Examples

The suffix “S” can be added to the end of other words to change their meaning. It can show that there is more than one thing [plural], that something belongs to someone [possessive], or that someone is doing something [third-person singular verbs tense]. This post will explain how to use “S” and give examples to help you understand.

The suffix “S” changes the meaning of a word in 3 ways:
Plural: More than one.
“book” becomes “books.”
Possession: It shows ownership.
“John’s book.“
Third-person singular tense: It is used for verbs to indicate a singular subject.
“John runs to school.” (third-person singular).

Keep reading to learn more about the suffix “S” and how to use it correctly in your writing. As a thank you, you can download a free PDF guide with additional exercises and examples. Mastering the suffix “S” will improve your grammar and make your writing more effective.

Understanding the Suffix S: Grammar Rules and Examples

Is ‘S’ a suffix?

Yes, the letter ‘S’ is a suffix. It is used to make plural nouns, show possession, and create the third-person singular verb tense with singular subjects.

The Suffix S – Making Singular Nouns Plural

Plural is a form of a noun that refers to more than one person or thing. Many nouns are made plural by adding the suffix S to the end of the word.

Singular	Plural
dog	dogs
friend	friends
smartphone	smartphones
train	trains
store	stores

*But there are also many nouns that are made plural by adding a different suffix. You can learn more at my blog post Singular and Plural nouns – 50 examples (worksheet PDF)

The Suffix S – Showing Possession

The most common way to show possession with singular nouns is to add an apostrophe (‘) and an “s” to the end of the noun. For example:

This is John’s book. (The book belongs to John.)
That is the cat’s food. (The food belongs to the cat.)

Plural Nouns

For plural nouns that end in “s,” simply add an apostrophe after the “s.” This indicates possession for the entire group.

The boys’ toys (The toys belong to the boys.)
The girls’ books (The books belong to the girls.)

Irregular Plural Nouns

If the plural noun is irregular, you still add an apostrophe and an “s” to show possession.

Men’s clothing (The clothing belongs to men.)
Children’s toys (The toys belong to children.)

Exceptions

While the general rules are straightforward, there are a few exceptions to keep in mind:

Names ending in “s”: If a name ends in “s,” you can either add an apostrophe and an “s” or just an apostrophe. Both are considered correct.

James’s car (or James’ car)

Joint possession: When two or more people own something together, you only add an apostrophe and an “s” to the last name.

John and Mary’s house (The house belongs to both John and Mary.)

The Suffix S – Third-Person Singular Verb Grammar

The pronouns – he, she, it + any name, position, or relation that describes one single person or thing are third-person singular subjects. These subjects are followed by verbs with an S (or ES) added to the end.

The following is from my blog post: Third-Person Singular – Your best Guide (Free 24-page eBook)

Third-person singular verbs – Spelling rules

Third-person singular subjects will add S or ES to the end of the verb describing their action. Using S or ES depends on the spelling of the verb. Here is an easy guide. We need to add ES to the following verbs:

Verbs ending with ss

miss – misses – “Don’t pass to Kyle, he misses every time!”
kiss – kisses – “My Mom kisses my baby brother every night before he goes to sleep.”

Verbs ending with sh or ch

brush – brushes – “Jenny brushes her teeth for 20 minutes every night before bed.”
match – matches – “This tie is perfect. It matches my shirt.”

Verbs ending with X

fix – fixes – “Allen fixes the computers in his office.”
mix –mixes – “Joan never mixes business with pleasure.”

Verbs ending with o

do – does – A: “My friend always draws funny pictures in his notebook.”
B: “My brother does that too.”
go – goes – “My Mom kisses my baby brother every night before he goes to sleep.”

Verbs ending with Y that come after a consonant

(The y changes to i before adding es)

fly – flies – “A bat flies through the night sky.”
try – tries – “Howard is not the best player on the team, but he tries hard.”

*If a verb ends with the letter Y that comes after a vowel (A, E, I, O, U) we just need to add the letter S.

“Leonard plays baseball.”
“My friend at work always buys his lunch.”

Frequently Asked Questions about The Suffix S

1. When do I use “s” to show possession?

You use “s” to show possession with singular nouns, such as “John’s book” or “the cat’s toy.” For plural nouns ending in “s,” add an apostrophe after the “s” (e.g., “the boys’ toys”).

2. Can “s” be used for both singular and plural nouns?

Yes, “s” can be used for both singular and plural nouns. For singular nouns, it indicates possession or third-person singular tense. For plural nouns, it indicates possession. Look for the apostrophe (‘).

3. What is the difference between “its” and “it’s”?

“Its” is a possessive pronoun, while “it’s” is a contraction of “it is.” For example:

“The cat lost its toy.” (possessive)
“It’s raining outside.” (contraction)

Understanding the Suffix S: Grammar Rules and Examples

Is ‘S’ a suffix?

The Suffix S – Making Singular Nouns Plural