Irregular Plural Nouns

Prev Article Next Article

Irregular plural nouns are nouns that do not follow the standard rule of adding “-s” or “-es” to form the plural. Instead, they change in different ways, such as changing vowels (man → men), adding “-ves” (leaf → leaves), or staying the same (sheep → sheep). These irregular forms can be confusing for English learners, but mastering them will improve your grammar and fluency in both spoken and written English.

In this article, we’ll explore different types of irregular plural nouns, provide common examples with sentences, and help you avoid common mistakes. At the end, test your knowledge with a 10-question quiz!

Table of Contents

Types of Irregular Plural Nouns

1. Changing the Vowel

Some nouns change the vowel sound in the plural form:

Singular	Plural	Example Sentence
Man	Men	There are ten men in the room.
Woman	Women	The company hired five women.
Foot	Feet	My feet hurt after walking all day.
Tooth	Teeth	I have two missing teeth.
Goose	Geese	We saw a flock of geese by the lake.

2. Changing “-f” or “-fe” to “-ves”

Some nouns ending in “-f” or “-fe” change to “-ves” in the plural:

Singular	Plural	Example Sentence
Wolf	Wolves	There are many wolves in the forest.
Leaf	Leaves	The tree’s leaves turned yellow.
Knife	Knives	Be careful with sharp knives.
Life	Lives	Many lives were saved by the doctor.
Wife	Wives	The two men talked about their wives.

3. Changing to a Completely Different Word

Some words completely change in the plural form:

Singular	Plural	Example Sentence
Child	Children	The school is full of children.
Person	People	Many people came to the event.
Mouse	Mice	We saw three mice in the kitchen.
Louse	Lice	The child had lice in his hair.
Die	Dice	He rolled the dice in the game.

4. Staying the Same

Some nouns do not change at all in the plural form:

Singular	Plural	Example Sentence
Sheep	Sheep	There are five sheep in the field.
Deer	Deer	We saw three deer in the forest.
Fish	Fish	I caught two fish in the river.
Moose	Moose	A moose crossed the road.
Aircraft	Aircraft	The aircraft is ready for takeoff.

Note: Some people use “fishes” when referring to different species of fish.

5. Foreign Words That Follow Their Original Language Rule

Some nouns borrowed from Latin, Greek, and other languages keep their original plural forms:

Singular	Plural	Example Sentence
Cactus	Cacti	The desert has many cacti.
Radius	Radii	The scientist measured the radii of the circles.
Datum	Data	The research is based on data.
Medium	Media	Social media is very popular.
Crisis	Crises	The country faced two economic crises.

Exceptions & Special Cases

Some nouns have two correct plural forms:

Octopus → Octopuses / Octopi (Both are correct.)
Cactus → Cactuses / Cacti (Both are used.)
Focus → Focuses / Foci (Scientific use prefers “foci.”)

Some nouns look plural but are singular:

News → The news is important.
Mathematics → Mathematics is difficult.
Physics → Physics is my favorite subject.

Some nouns look singular but are plural:

Scissors → The scissors are sharp.
Glasses → My glasses are broken.
Trousers → His trousers are new.

Irregular Plural Nouns – Quiz

1. What is the correct plural of “child”?

a) Childs
b) Childrens
c) Children

2. Which sentence is correct?

a) My foots hurt.
b) My feet hurt.
c) My feets hurt.

3. What is the plural of “person”?

a) People
b) Persons
c) Peoples

4. “There are many ___ in the forest.” (deer)

a) Deers
b) Deer
c) Deeres

5. The plural of “tooth” is:

a) Tooths
b) Teeth
c) Teeths

6. Which sentence is correct?

a) I have two knifes.
b) I have two knives.
c) I have two knivies.

7. What is the plural of “mouse”?

a) Mouses
b) Mices
c) Mice

8. The plural of “crisis” is:

a) Crisises
b) Crises
c) Crisis

9. “The ___ are flying in the sky.” (aircraft)

a) Aircraft
b) Aircrafts
c) Aircrafs

10. What is the correct plural of “goose”?

a) Gooses
b) Geese
c) Goose

Quiz Answers

1) Children
2) My feet hurt.
3) People
4) Deer
5) Teeth
6) I have two knives.
7) Mice
8) Crises
9) Aircraft
10) Geese

Prev Article Next Article