Irregular plural nouns are nouns that become plural in a way other than adding -s or -es to the end. It can be tough to remember which nouns are irregular, but here are a few guidelines for how to handle the ones that are.
Regular Nouns
First off, a noun is a person, place, or thing. Nouns are singular when they represent one item and plural when they represent more than one. To make a regular noun plural, all you have to do is add -s or -es to the end. Girls, for example, is the plural form of the word girl, and pots is the plural form of the word pot.
Regular nouns that end in -s, -ss, -sh, -ch, -x, or -z become plural with the addition of -es. So box becomes boxes, and dish becomes dishes.
Irregular Nouns That Don’t Change
Not all nouns follow the same rules. Some are exactly the same in their singular and plural forms. The word sheep, for instance, can mean one woolly animal or many woolly animals. The word aircraft can mean one airplane or many airplanes.
At the same time, some irregular nouns only exist in their plural form. For example, there’s no singular form of scissors, pants, species, or shorts.
Irregular Nouns That End in -Y
Some irregular nouns that end in -y are made plural by changing the y to an i and adding -es. For instance, baby becomes babies, and lady becomes ladies. But, if it ends in a vowel followed by y, it’s actually a regular noun. For example, “Santa brings toys to children by climbing down their chimneys.”
Irregular Nouns That End in -F
An irregular noun that ends in -f becomes plural by changing the f to a v, and adding -es. So thief becomes thieves, and loaf becomes loaves. Similarly, if a noun ends in the letters fe, you make it plural by changing the f to a v and adding -s, as in “A human has only has one life, but cats are believed to have have nine lives.”
Irregular Nouns That End in -Us
Some irregular nouns end in -us, like alumnus and cactus. To make these words plural, drop the -us and add an -i. For instance, “Many colleges request donations from alumni.” There are, of course, exceptions to this rule. For instance, the aforementioned alumni attended different college campuses, not college campi.
Irregular Nouns That Change Completely
Some irregular nouns don’t follow any established rules to become plural. For example, the plural of person is people, the plural of woman is women, and the plural of goose is geese. Similarly, mouse becomes mice in its plural form, while house becomes houses.
