What are Irregular Nouns in English? List of 25 Irregular Plural Nouns & Examples

Have you ever felt like the plural noun rules in English throw curveballs at you just when you thought you had them figured out? If yes then, you might have entered the realm of irregular nouns. These grammatical tools refuse to follow the “add an ‘s’ or ‘es’ and call it a day” rule. They pluralise nouns like “tooth” as “teeth”, “woman” to “women”, and so on as a part of irregular plural nouns. 

No doubt these linguistic Houdinis can leave even the most confident grammar nazi tongue-tied. Therefore, this blog article is specially designed to deal with all your confusion regarding Irregular nouns. So, hop on and sail through the examples and exercises with us henceforth to emerge as a proficient English speaker later on. 

[powerkit_toc title=”This Blog Includes:”

Must Read: Singular vs. Plural Nouns: Learn Key Differences

What are Irregular Nouns and Examples?

As per the standard definition, Irregular nouns, as a part of the Noun kingdom, do not follow the set rules for forming a singular noun into a plural. To elaborate, most nouns pluralise with a simple addition of a ‘s/es’ at the end of a singular word. But, irregular nouns have unique plural forms that do not adhere to this pattern. 

Take a look at the example below and you will understand the definition of irregular plural nouns even better. 

Singular	Irregular Plural
Goose	Geese
Person	People
Child	Children
Foot	Feet
Cactus	Cacti
Criterion	Criteria

List of 25 Irregular Plural Nouns You Should Know

Just like the examples above, there are many more irregular nouns you will encounter in the journey of mastering along with the other rules in grammar. So, make sure to go through the listicles below carefully for future reference.

1. Child ➡️ Children
2. Tooth ➡️ Teeth
3. Woman ➡️ Women
4. Man ➡️ Men
5. Foot ➡️ Feet
6. Mouse ➡️ Mice (Note: “Mouses” also acceptable for some contexts)
7. Louse ➡️ Pural: Lice
8. Goose ➡️ Geese
9. Ox ➡️ Oxen
10. Die ➡️ Dice
11. Penny ➡️ Pence
12. Criterion ➡️ Criteria
13. Datum ➡️ Data
14. Radius ➡️ Radii
15. Syllabus ➡️ Syllabi
16. Phenomenon ➡️ Phenomena
17. Crisis ➡️ Crises
18. Hypothesis ➡️ Hypotheses
19. Thesis ➡️ Theses
20. Oasis ➡️ Oases
21. Cactus ➡️ Cacti (or Cactuses)
22. Fungus ➡️ Fungi
23. Genus ➡️ Genera
24. Nucleus ➡️ Nuclei
25. Stimulus ➡️ Stimuli

Quick Read: Singular and Plural for Class 2 Kids

Irregular Nouns Example Sentences 

The following example sentences of irregular nouns will take you another step closer to gaining confidence in their usage in English:

1. The old woman gazed fondly at her grandchildren, reminiscing about her childhood.
2. The dentist advised brushing with fluoride toothpaste to strengthen your teeth.
3. A group of women gathered in the park, advocating for equal rights.
4. The lone cowboy herded his cattle, watching them graze on the vast plains.
5. The detective meticulously examined the dice, searching for clues.
6. The children delighted in collecting shiny new pennies found on the sidewalk.
7. The professor presented his groundbreaking research, outlining his key criteria for evaluation.
8. With new data emerging, the scientist revised his initial hypothesis.
9. The university announced changes to its syllabi for the upcoming semester.
10. The doctor explained that the patient was experiencing a rare neurological phenomenon.

Irregular Nouns Exercise to Practise Right away

Whenever you feel ready, try to test your understanding of irregular nouns with the following exercise and check your answers later once you are done. 

Instructions: Fill in the blanks with the correct plural form of the irregular noun in parentheses.

1. I brushed my ________ (tooth) thoroughly before bed. 
2. The farmer watched his ________ (cow) graze in the field. 
3. The child left several ________ (penny) on the counter.
4. We need to consider more ________ (criterion) before making a decision. 
5. The detective examined the various ________ (footprint) at the crime scene. 
6. The ________ (goose) honked loudly as they flew overhead. 
7. The museum exhibit showcased several ancient ________ (mummy). 
8. The scientist analyzed the collected ________ (datum) to conclude. 
9. The ________ (cactus) in the desert bloomed beautifully after a rare rainfall. 
10. The audience erupted in ________ (applause) after the musician’s performance. 
11. The ________ (syllabus) for the class included interesting reading materials.
12. The doctor explained the possible ________ (side effect) of the medication. 
13. The children played hide-and-seek, giggling uncontrollably in their hiding ________ (place). 
14. The author presented several ________ (hypothesis) in their new book. 
15. The team celebrated their victory with loud ________ (cheer). 

16. The ________ (phenomenon) of the Northern Lights captivated the tourists. 
17. The teacher explained the different ________ (genus) of plants in the garden. 

Answers Key

1. teeth
2. cattle
3. pennies
4. criteria
5. footprints
6. geese
7. mummies
8. data
9. cacti
10. applause
11. syllabi
12. side effects
13. places
14. hypotheses
15. cheers
16. phenomena
17. genera

Find more interesting reads on nouns here!

What are Singular Nouns?	Plural Nouns
What are Material Nouns?	Compound Nouns
Countable and Uncountable Nouns	What are Possessive Nouns?

This was all about irregular nouns and their relevant information. Hope you understand the concept and know how to proceed. You can also follow Leverage Edu for more exciting and informative blogs.