Why English Has So Many Irregular Plurals – Foot to Feet, Mouse to Mice
If you’re learning English, you quickly encounter the standard rule for making a noun plural: just add -s. Car becomes cars, book becomes books, and idea becomes ideas. Simple!
Then you hit the exceptions: foot transforms into feet, man becomes men, and child becomes children. These handful of common words—the irregular plurals—don’t follow the rules. They are not random mistakes; they are linguistic fossils, providing a fascinating glimpse into the deep history of the English language.
The short answer to why these English irregular plurals exist? They are survivors. They resisted the grammatical changes that simplified English over a thousand years ago. Let’s delve into the three main types of these tenacious linguistic relics.
1. The Vowel Changers (Ablaut Plurals) 🦷
The most recognizable group of irregular plurals forms their plural by changing the vowel sound inside the word, a process linguists call ablaut or vowel gradation. This was the original, ancient Germanic way of making nouns plural.
How it Worked: The Foot Example
In the ancestor of English (Old English, or Anglo-Saxon), the plural form of nouns was often signaled by a change in the vowel sound, usually triggered by a suffix that has since been lost.
- The singular fōt (foot) had a plural form fēt (feet).
- The singular mūs (mouse) had a plural form mȳs (mice).
As English evolved, the easy -s ending became the universal standard for new words and less common nouns. However, because words like foot, man, and tooth were used constantly—daily, hourly—their ancient, distinctive vowel-change plurals were too deeply ingrained in the language to be forgotten.
Here are the primary vowel-change survivors:
- oo → ee: foot → feet, tooth → teeth, goose → geese
- a → e: man → men, woman → women (The pronunciation of woman changes drastically in the plural, even though the vowel change is less obvious in the spelling).
- ou → i: mouse → mice, louse → lice
2. The Old Suffix Survivors (The -en Plurals) 🐂
Another small group of irregular nouns retains a very old, distinctive plural suffix: -en. This was a different plural ending common in Old English, distinct from the later, dominant -s ending.
The Child and Ox Story
The most famous examples are:
- Child → Children
- Ox → Oxen
The word child is actually doubly irregular! In Old English, the plural was cildru. Later, the redundant -en ending (from a separate grammatical class) was added to the existing plural form, resulting in the modern children. This process is a rare example of English grammar adding a complexity that didn’t exist before, solidifying its status as one of the most stubborn irregular plurals in English.
3. The Zero Plurals (Same Singular and Plural) 🦌
A third category of irregular plurals simply makes no change at all. These zero plurals use the same form for both singular and plural.
This phenomenon is common in words related to animals, especially those that were historically hunted or herded for food.
- Deer → Deer
- Sheep → Sheep
- Fish → Fish (though fishes is used when referring to different species of fish).
- Series → Series (borrowed from Latin with an unchanging form).
Linguists theorize that keeping the same form for these zero plural nouns was simply practical and efficient for people who spoke a simplified, mixed language (like the Old English speakers who interacted with Viking Norse speakers).
Why We Don’t Say Gooses or Mans
The reason these irregular English plurals have survived while thousands of other Old English strong verbs and irregular nouns adopted the simple -s ending comes down to a linguistic principle: frequency of use.
- High Frequency = High Resistance: The nouns that maintain their archaic, vowel-changing forms (foot, man, tooth) are among the most frequently used words in the entire language.
- The Power of Habit: The more often a word is used, the more deeply its peculiar form is lodged in the brain’s linguistic memory. It is simply faster for a speaker to retrieve the established word men than to mentally apply the new, regular rule to create the never-used word mans.
As English continues to evolve, these irregular nouns stand as resilient monuments to its Germanic origins. While they may be frustrating for language learners, they are a powerful reminder of the turbulent, borrowing, and ever-changing history of the English vocabulary. They are the exceptions that prove the depth of the rule!