Plural of Series Explained: The Simple Truth You Need to Know
Quick Answer
The plural of series is series. The word never changes. One series, two series, ten series — always the same.
One: I am watching a series on TV.
Many: There are three series I want to watch.
One Series, Two Series — See the Pattern
Look at these examples. Can you see what happens?
- I watched a series last night. (one)
- She has read three series of books this year. (more than one)
- This series of lessons is very helpful. (one)
- Both series are available online. (more than one)
Did you see the pattern? The word series looks exactly the same every time. It does not change for one or for many. The words around it tell you the number.
| One (singular) | More than one (plural) |
|---|---|
| series | series |
Some other English words work the same way:
| One (singular) | More than one (plural) |
|---|---|
| sheep | sheep |
| deer | deer |
| species | species |
| aircraft | aircraft |
How to Tell if Series Means One or Many
If the word never changes, how do you know if someone means one series or many? You look at the words around it.
Words that show ONE series:
- a / this / one series → A series is on tonight.
- this series → This series has ten episodes.
- one series → Only one series was any good.
Words that show MANY series:
- many / both / these series → Many series are on Netflix.
- two / three / several series → He watched three series last month.
- these series → These series were all very popular.
Easy way to remember: Look at the verb. If it is is or was, it is one. If it is are or were, it is many.
The Rule in One Line: Series never changes — one series, many series. Use the verb to show one or many.
How to Use Series in Everyday English
- I am watching a new series on Netflix. (one series)
- There are many good series to choose from. (more than one)
- This series of exercises is great for beginners. (one series, so we use “is”)
- Both series are worth watching. (two series, so we use “are”)
- She finished three book series last summer. (more than one)
You are doing great. Now let’s look at the mistakes many learners make with this word.
The Most Common Mistake With Series
Many learners try to say “serieses” to show more than one. This is very common — your brain wants to add -es because that is the normal English rule. But do not worry, you are not alone. Even native speakers sometimes feel unsure about this word.
Mistake 1: Adding -es for many
✗ I watched two serieses last week.
✓ I watched two series last week.
Mistake 2: Removing the -s to make it singular
✗ This serie is very good.
✓ This series is very good.
Mistake 3: Using the wrong verb
✗ Both series is available online.
✓ Both series are available online.
How to remember: The word series already ends in -ies. Do not add anything to it. Do not take anything away. It stays exactly the same, always.
Other words like this: sheep → sheep, deer → deer, fish → fish, species → species, aircraft → aircraft.
Test Yourself: Series or Serieses?
Choose the correct answer for each sentence. Click Check to see if you are right.
1. I am watching a really good _______ on TV right now.
2. There are three _______ of books on the shelf.
3. This series of lessons _______ very helpful for beginners.
4. Both series _______ worth watching.
5. She has finished two _______ this month.
Keep Going — You Are Building Something
You just learned that series never changes — one series, many series, always the same. That is one more tricky plural you will never get wrong again.
But here is something interesting. The word deer works the same way — one deer, many deer. But what about a baby deer? Is it a “baby deer” or is there a completely different word for it? And what happens when you talk about different types of deer — does the word change then?
Next lesson: What Is the Plural of Deer?
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My name is Khamis Maiouf. I am the creator of the English Teacher Site, dedicated to providing valuable resources and insights for students around the world. With a passion for education and a commitment to helping students enhance their skills, I aim to make English teaching more effective and enjoyable for both educators and students.
