What’s the Plural of Vertex: Understanding Geometric Terms
Quick Answer
The plural of vertex is vertices. You can also say vertexes, but vertices is much more common. For example: “A triangle has three vertices.”
Vertex, Vertices — See the Pattern
Look at these sentences. Can you see how the word changes?
- A square has one vertex at each corner. (one point)
- A triangle has three vertices. (three points)
- The teacher asked us to count the vertices of the shape. (more than one)
- Each vertex is where two lines meet. (one point)
Did you see the pattern? When there is one point, we say vertex. When there are two or more, we say vertices.
| How many? | Word | Example |
|---|---|---|
| One | vertex | This is one vertex. |
| Two or more | vertices | A cube has eight vertices. |
Why Vertex Becomes Vertices (Not Vertexes)
The word vertex comes from Latin. In English, many Latin words that end in -ex change to -ices in the plural. You drop the -ex and add -ices.
- vertex → vertices (drop -ex, add -ices)
- index → indices (same pattern)
- apex → apices (same pattern)
You can say “vertexes” — it is not wrong. But “vertices” is the form you will see in school, in textbooks, and in maths class. If you learn vertices, you will always sound right.
Easy way to remember: Think of the word “vertices” like “vert + ices” — the ending sounds like “ice” with an S. Vertex → vert-ices.
The Rule in One Line: One vertex, two or more vertices — drop the -ex, add -ices.
How to Use Vertex and Vertices in Everyday English
- “How many vertices does a triangle have?” — “Three.” (counting corners of a shape)
- “Mark each vertex with a dot.” (one corner at a time)
- “The two vertices at the top are the same distance apart.” (two specific corners)
- “A cube has eight vertices, twelve edges, and six faces.” (describing a 3D shape)
- “Draw a line from one vertex to the opposite vertex.” (talking about two single points)
You are doing great. Now let us look at the mistakes many learners make.
The Most Common Mistakes With Vertex and Vertices
Even advanced learners get confused by Latin plurals — so if you mix these up, you are not alone. Many native English speakers also say “vertexes” instead of “vertices” in everyday speech.
✗ “The shape has five vertexs.”
✓ “The shape has five vertices.”
✗ “Count all the vertex of this shape.”
✓ “Count all the vertices of this shape.”
✗ “Each vertices is important.”
✓ “Each vertex is important.”
How to remember: “Vertex” ends in X — it is one point (like an X marks one spot). “Vertices” ends in S — it is more than one (S = several).
Other words that follow this pattern: index → indices, apex → apices, vortex → vortices. If you learn the -ex → -ices rule, you can use it for all of these words.
Test Yourself: Vertex or Vertices?
Choose the correct answer for each sentence. Click Check to see if you are right.
1. A triangle has three _______.
2. Mark the _______ where the two lines meet.
3. How many _______ does a cube have?
4. Each _______ of the shape is marked with a red dot.
5. The _______ of the pyramid all connect to the top point.
Keep Going — You Are Building Something
You just learned the plural of vertex. That is one more Latin-origin word you will never get wrong again.
But here is something strange. The word ox does not follow any Latin rule — and its plural is not “oxes.” It is one of the oldest and most unusual plurals in the English language. Can you guess what it is?
Next lesson: Oxen or Oxes? 5 Easy Tips to Never Get It Wrong
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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.
