What’s the Plural of Fungus: Understanding the Correct Form
Quick Answer
The plural of fungus is fungi. You can also say “funguses,” but fungi is the most common form.
One: There is a fungus on the bread.
More than one: There are fungi growing in the garden.
Fungus, Fungi, Funguses — See the Pattern
Read these sentences. Can you see the pattern?
- That fungus on the tree looks strange.
- Scientists found many fungi in the forest.
- Some fungi are safe to eat, but others are not.
- A new fungus was discovered last year.
Did you see it? When there is one, we say fungus. When there are more than one, we say fungi.
| Singular (one) | Plural (more than one) |
|---|---|
| fungus | fungi |
Why Fungus Becomes Fungi (Not Funguses)
The word fungus comes from Latin. In Latin, words that end in -us change to -i when they become plural. English keeps this old rule for some words.
- fungus → fungi (change -us to -i)
- cactus → cacti
- stimulus → stimuli
You might also hear people say funguses. This follows the normal English rule of adding -es. It is not wrong, but fungi is much more common — especially in writing and at school.
Easy way to remember: Think of the pattern: -us becomes -i. Fungus → fungi. Just like cactus → cacti.
The Rule in One Line: One fungus, many fungi — change -us to -i.
Real-Life Examples With Fungus and Fungi
- There are many types of fungi in this park. (= more than one kind)
- That fungus on the wall looks like it is growing fast. (= just one)
- Mushrooms are a type of fungus. (= one group)
- The doctor said the skin problem was caused by a fungus. (= one thing)
- Some fungi help plants grow, while others damage them. (= different kinds)
You are doing great. Now let’s look at the mistakes many learners make.
Two Mistakes to Avoid With Fungus and Fungi
Even advanced English speakers sometimes get confused with Latin plurals — so if you mix these up, you are not alone. Here are the two biggest mistakes:
Mistake 1: Using “fungus” when you mean more than one
✗ There are many fungus in the forest.
✓ There are many fungi in the forest.
✗ These fungus can make you sick.
✓ These fungi can make you sick.
Mistake 2: Using “fungi” when you mean just one
✗ I found a fungi on the bread.
✓ I found a fungus on the bread.
How to remember: Look at the words around it. Do you see a, one, or this? Use fungus (singular). Do you see many, some, these, or a number? Use fungi (plural).
Other words that follow the same Latin rule: cactus → cacti, stimulus → stimuli, nucleus → nuclei, radius → radii.
Test Yourself: Fungus or Fungi?
Choose the correct answer for each sentence. Click Check to see if you are right.
1. Scientists discovered many new _______ in the rainforest.
2. There is a strange _______ growing on that old log.
3. Some _______ can be used to make medicine.
4. The doctor told her that a _______ caused the infection.
5. These _______ are safe to eat — they are just mushrooms.
Keep Going — You Are Building Something
You just learned the plural of fungus. That is one more Latin plural you will never get wrong again.
But here is a fun question: what is the plural of cactus? Is it cactuses or cacti? It follows the same Latin pattern — but there is a twist that surprises most learners.
Next lesson: What’s the Plural of Cactus?
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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.
