Forming Regular and Irregular Plural Nouns

Nouns are an essential part of any language, and understanding how to form their plural is crucial for effective communication.

In English, there are rules for forming plural nouns, but there are also many exceptions to those rules. This post will cover the different ways of forming regular and irregular plural nouns.

Forming Regular Plurals in English

One of the most common ways of forming the plural of regular nouns is by adding -s to the singular form. The table below shows some examples:

Singular	Plural
Cat	Cats
Book	Books
Chair	Chairs
Car	Cars

Forming the Plural of Nouns Ending in -s, -x, -ch, and -sh

For nouns that end in -s, -x, -ch, and -sh, the plural is formed by adding -es to the singular form. Some nouns that end in -z also double their ending consonant, like quizzes. The table below shows some examples:

Singular	Plural
Bus	Buses
Fox	Foxes
Church	Churches
Dish	Dishes
Quiz	Quizzes
Buzz	Buzzes

Forming the Plural of Nouns Ending in -fe and -f

For nouns that end in -fe, the plural is formed by changing the -f to -v and adding -es. For nouns that end in -f, the plural is formed by adding -s. The table below shows some examples:

Singular	Plural
Life	Lives
Wife	Wives
Leaf	Leaves
Calf	Calves
Shelf	Shelves
Chef	Chefs

Forming the Plural of Nouns Ending in -y

For nouns that end in -y, and the preceding letter is a consonant, the plural is formed by changing the -y to -i and adding -es.

For nouns that end in -y, and the preceding letter is a vowel, the plural is formed by adding -s. The table below shows some examples:

Singular	Plural
Spy	Spies
City	Cities
County	Counties
Monkey	Monkeys
Boy	Boys
Key	Keys

Forming the Plural of Nouns Ending in -o

Most nouns ending in -o add the plural suffix -es, but many words with a foreign origin simply add -s. The table below shows some examples:

Singular	Plural
Potato	Potatoes
Tomato	Tomatoes
Hero	Heroes
Piano	Pianos
Zoo	Zoos

Forming the Plural of Irregular Nouns

Some nouns do not follow any rules when forming the plural, and they are considered irregular. Some examples of irregular plural nouns include children, goose, and mice. The table below shows some examples:

Singular	Plural
Child	Children
Goose	Geese
Mouse	Mice
Tooth	Teeth
Foot	Feet

Read our full list of irregular plural nouns.

Nouns That Do Not Change in the Plural

There are also some nouns that do not change in the plural form. These include moose, fish, deer, aircraft, and others. The table below shows some examples:

Singular	Plural
Fish	Fish
Deer	Deer
Moose	Moose
Aircraft	Aircraft

Irregular Plural Nouns with Latin and/or Greek Origin

Many English words have their roots in Latin and Greek languages, and some of these words have unique rules for forming plurals.

While many English plurals follow a consistent pattern, there are some specific patterns for words of Greek and Latin origin. Understanding their pluralization requires memorization and understanding of their linguistic origins.

The following rules are all examples of plural rules of Latin and Greek origin.

Pluralization of Nouns Ending in -is

Nouns ending in -is that are derived from Latin and Greek often have an irregular plural form that changes the -is ending to -es.

Singular	Plural
Crisis	Crises
Analysis	Analyses
Basis	Bases
Diagnosis	Diagnoses
Oasis	Oases

Pluralization of Nouns Ending in -us

Nouns ending in -us that are derived from Latin often have an irregular plural form that changes the -us ending to -i.

Some of these words however also have anglicized plural forms, formed by adding -es . In such instances both plurals are grammatically correct.

Singular	Plural	Alternative
Cactus	Cacti	Cactuses
Focus	Foci	Focuses
Radius	Radii	Radiuses
Platypus	Platypi	Platypuses

Pluralization of Nouns Ending in -on

Nouns ending in -on that are derived from Greek often have an irregular plural form that changes the -on ending to -a.

These nouns can also be pluralized in a more modern way of simply adding an -s to the end of the word.

Singular	Plural	Alternative
Phenomenon	Phenomena	Phenomenons
Criterion	Criteria	Criterions

Pluralization of Nouns Ending in -um

Nouns ending in -um that are derived from Latin often have an irregular plural form that changes the -um ending to -a.

This is another group of nouns which can be pluralized in a more modern form of English by adding -s to the end of the word.

Singular	Plural	Alternative
Medium	Media	Mediums
Curriculum	Curricula	Curriculums
Memorandum	Memoranda	Memorandums
Forum	Fora	Forums

Pluralization of Nouns Ending in -ix or -ex

Nouns ending in -ix or -ex that are derived from Latin often have an irregular plural form that changes the -ix or -ex ending to -ices or -es.

You can also form some of these plurals by adding the suffix -es to the end of the word.

Singular	Plural	Alternative
Index	Indices	Indexes
Appendix	Appendices	Appendixes
Matrix	Matrices	Matrixes
Vertex	Vertices	Vertexes

Conclusion

Forming plural nouns in English can be challenging, as there are many rules to follow, but also many exceptions to those rules. The most important thing is to learn the different patterns and practice using them. By mastering plural nouns, you can improve your writing and speaking skills and avoid common mistakes.

One helpful tip is to read extensively in English and take note of how plural nouns are used in context. This will help you understand the rules and exceptions better and also give you a feel for the language.

Additionally, you can use online resources such as GrammarGiant's plural list and grammar books to reinforce your understanding and to check your work.