Irregular Plurals of Nouns
Introduction
Although most nouns have plurals formed according to regular rules (see Regular Plurals of Nouns), some nouns have unusual, or irregular plurals. This page will introduce the most common ones, so that you can learn them.
Types of irregular plural
There are many types of irregular plural, but these are the most common:
| Noun type | Forming the plural | Example |
|---|---|---|
| Ends with -fe | Change f to v then Add -s |
knife  kniveslife liveswife wives |
| Ends with -f | Change f to v then Add -es |
half halves wolf wolvesloaf loaves |
| Ends with -o | Add -es | potato potatoes tomato tomatoesvolcano volcanoes |
| ends with -us | Change -us to -i | cactus cacti nucleus nucleifocus foci |
| ends with -is | Change -is to -es | analysis analyses crisis crisesthesis theses |
| ends with -on | Change -on to -a | phenomenon phenomena criterion criteria |
| ALL KINDS | Change the vowel or Change the word or Add a different ending |
man men foot feetchild childrenperson peopletooth teethmouse mice |
| Unchanging | Singular and plural are the same |
sheep deer fish (sometimes) |
When you are sure that you understand the lesson, you can continue with the exercises.