Irregular Plural Nouns—Rules to Help You Form the Plural

Certain words don’t follow the general plural noun rules, which are adding an –s or –es at the end of the noun, and these are called irregular plural nouns. Making them plural requires knowing a specific spelling rule that will help you change them from singular to plural.

It may sound a bit overwhelming, but we will tell you how they work to make things easier for you.

Rules to change irregular plural nouns from singular to plural

Here are the most common spelling rules for irregular nouns:

Irregular nouns with –f or –fe endings

Nouns such as leaf, knife, calf, wife, and life make their plural by changing their –f or –fe ending to –ves. To make things easier for you, remember that –f becomes –v and then you just add the common plural noun ending –es.

Example:

Wife – wives

Leaf – leaves

Irregular nouns with –o ending

To make plural from nouns ending in –o, such as torpedo, veto, potato, and tomato, you just need to add –es without changing anything.

Example:

Torpedo – torpedoes

Tomato – tomatoes

Irregular nouns with –is ending

To change these nouns from singular to plural, change –is to –es:

Example:

Crisis – crises

Oasis – oases

Irregular nouns that change their vowels

If the singular noun is man, the plural is men. Rings a bell? Well, this is not the only irregular noun that has to change its vowels to form the plural. These nouns change an to en, or oo to ee.

Example:

Tooth – teeth

Woman – women

Irregular nouns: examples of words that change considerably

Here are some of the most common nouns that change in spelling drastically when made plural:

Examples:

Child – children

Mouse – mice

Person – people

Ox – oxen

Die – dice

Irregular nouns that stay the same

Sheep is a common but not the only irregular plural noun that has the same spelling for both singular and plural.

Examples:

Deer – deer

Fish – fish

Irregular nouns ending in –us

Even though there aren’t many nouns with this ending, it’s still good to know how to make them plural. You just have to use –i instead of –us.

Examples:

Nucleus - nuclei

Fungus – fungi