What’s the Plural of Synthesis: Understanding Singular and Plural Forms in English
Quick Answer
The plural of synthesis is syntheses. The word “synthesises” is not correct in English.
One: The teacher showed us a synthesis of two ideas.
More than one: The book has many syntheses of old and new theories.
Synthesis Becomes Syntheses — See the Pattern
Look at these words. Can you see what happens at the end?
- one synthesis → two syntheses
- one analysis → two analyses
- one thesis → two theses
- one crisis → two crises
Did you see the pattern? The -is at the end changes to -es. This rule works for many English words that come from Greek.
| One (singular) | More than one (plural) |
|---|---|
| synthesis | syntheses |
| analysis | analyses |
| thesis | theses |
| hypothesis | hypotheses |
| crisis | crises |
Why It Is Syntheses and Not Synthesises
Most English plurals just add -s or -es to the end of the word: cat → cats, box → boxes. But the word synthesis comes from Greek. Greek words that end in -is follow a special rule. The -is changes to -es:
- synthesis → syntheses (not “synthesises”)
- analysis → analyses (not “analysises”)
- thesis → theses (not “thesises”)
A synthesis is when you put different things together to make something new. For example, when you mix two ideas to make one bigger idea, that is a synthesis. You say it like “SIN-thuh-sis” for one, and “SIN-thuh-seez” for more than one.
Easy way to remember: Think of analysis → analyses. They are sister words. Synthesis works the same way: synthesis → syntheses.
The Rule in One Line: Synthesis ends in -is, so the plural is syntheses (-is → -es).
How to Use Synthesis and Syntheses in Everyday English
- The chef made a synthesis of Italian and Japanese flavours. (one mix)
- The museum showed two syntheses of modern and old art. (more than one mix)
- Her essay is a synthesis of three different studies. (one combination)
- The teacher showed us many syntheses of Eastern and Western music. (more than one combination)
- This song is a synthesis of jazz and rock. (one combination)
You are doing great. Now let us look at the mistakes most learners make with this word.
The Most Common Mistakes With Synthesis
Many learners write “synthesises” because most English plurals just add -s or -es. That is a smart guess — but it does not work for words from Greek. Even advanced learners mix this up sometimes. So if you get confused, you are not alone.
✗ The book has many synthesises.
✓ The book has many syntheses.
✗ She wrote a clear synthes.
✓ She wrote a clear synthesis.
✗ Both synthesis were strong.
✓ Both syntheses were strong.
How to remember: The word ends in -is. If you see -is at the end, change it to -es. Synthesis → syntheses. Simple.
One small thing to watch: the spelling looks almost the same, but the sound changes. Synthesis ends with a soft “sis” sound. Syntheses ends with a “seez” sound, like “bees” or “trees”. If you say “seez” at the end, you are using the plural.
Other words like this: analysis → analyses, thesis → theses, hypothesis → hypotheses, crisis → crises, basis → bases.
Test Yourself: Synthesis or Syntheses?
Choose the correct answer for each sentence. Click Check to see if you are right.
1. The book showed two _______ of old and new ideas.
2. Her essay is a clear _______ of three studies.
3. The museum showed many _______ of art from different countries.
4. This song is a great _______ of pop and jazz.
5. The teacher gave us five short _______ to read for class.
Keep Going — You Are Building Something
You just learned that synthesis becomes syntheses. That is one more plural you will never get wrong again.
But here is something interesting. The word analysis follows the same Greek rule — and you hear it every day in the news, in school, and at work. Do you know how to talk about two analyses? It is the most useful word in this family.
Next lesson: What Is the Plural of Analysis?
Sources
Definition of synthesis — Merriam-Webster Dictionary
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.
