Grammar Irregular Plural Nouns |
The Blue Book of Grammar and Punctuation

Irregular Plural Nouns

In the English language nouns are commonly made plural by adding s or es. For example, car becomes cars and house becomes houses.

In this discussion, we’ll consider what irregular plural nouns are.

With irregular plural nouns, an s or es is not used to create the plural. This can sometimes cause confusion for users of English, particularly among those who are still learning the language. When forming an irregular plural, how are we supposed to know when to add a new ending, change the spelling, or just leave the word alone?

Memorization and recognition through reading and writing is usually the best way to understand what irregular plural nouns are and how to treat them. In the meantime, we can review several of the instances in which plural nouns become irregular.

Plurals with an Irregular Ending
Some nouns become non-standard plurals by adding endings other s or es.

For example, a farmer has one ox and two oxen (not oxes). A family might have one child or two children (not childs).

We also have one cactus but several cacti. If you write a book, it might have one appendix or several appendices.

Nouns That End in the Letter “F” or “Fe”
A farm has one calf or multiple calves. The “f” ending is changed with a “v” and “es” is added, creating a smoother transition from singular to plural.

Other examples are knife into knives and life into lives. The “f” is now a “v” and an es is added.

Nouns That End in the Letter “O”
You say tomatoe, I say tomato: This common discrepancy with the singular noun most likely stems from the fact that es is sometimes added to the end of a word to make it plural, as in tomato to tomatoes. Potato likewise becomes potatoes and hero becomes heroes.

Of course, as soon as we think we’re comfortable with a rule, English can still keep us guessing. When making a noun ending in o plural, the es rule can change, often when the noun is foreign.

For example, the beautiful Italian words piano and cello are made plural with only an s, becoming pianos and cellos.

Plurals with a Vowel Change
There are some words in English whose vowels switch to a different vowel to become plural.

woman > women
man > men
foot > feet
goose > geese

As you can see, the changes commonly take the form of double vowels such as ee or endings including a vowel shift from an to en. Once again, however, the rules with vowels in irregular plural nouns can change. As we’ve touched on, memorization and recognition by reading and writing English is the best way to achieve accuracy.

Nouns with a Total Spelling Change
Yet another rule for irregular plural nouns involves a complete spelling change when adjusting from singular to plural.

For example, we have one mouse as a pet but two mice. Many of us might also like to think of ourselves as a person who gets along well with other people.

No Change at All
Many nouns in English have the forbearance to not change at all (a welcome break from keeping track of so many rules).

Some examples include deer, fish, moose, shrimp, and buffalo. (And yes, these tend to be words for animals.)

Beauty in Diversity
The richness of English resides in its roots. Most English words stem from other languages (over 60 percent are from Latin or Greek) and reflect changes that adapt to how English is spoken.

We hope this review is helpful as you strengthen your understanding of what irregular plural nouns are. While not a complete discussion of the topic, it aims to inspire your awareness of irregular plurals, as well as your memorization of them through regular reading and writing of English.


Pop Quiz

Now that you better understand what irregular plural nouns are, choose the correct plural noun in each sentence.

1. While Dan and I were out on our snowmobiles, we saw several [moose / meese] run by.

2. Two [policemans / policemen] helped us get our cat, Fritter, down from the tree.

3. Janelle was thinking about planting a few [cacti / cactuses] in her backyard. 

4. Christopher has two new baby [tooths / teeth].

5. I’m not so sure that’s true—it sounds like an old [wives’ / wifes’] tale to me.


Pop Quiz Answers

1. While Dan and I were out on our snowmobiles, we saw several moose run by.

2. Two policemen helped us get our cat, Fritter, down from the tree.

3. Janelle was thinking about planting a few cacti in her backyard.

4. Christopher has two new baby teeth.

5. I’m not so sure that’s true—it sounds like an old wives’ tale to me.

If the article or the existing discussions do not address a thought or question you have on the subject, please use the "Comment" box at the bottom of this page.

10 responses to “Irregular Plural Nouns”

  1. Anissia says:

    I really enjoy the quizzes you post. My particular weakness is punctuation, so I have learned quite a bit from your quizzes and explanations.

  2. Mary Perez says:

    I enjoy the quizzes. I probably learn more from making mistakes on the quizzes and rereading the text to reinforce the concept.

  3. Mary Devereux says:

    I LOVED this article/email post – it made me chuckle. I’m not a “conspiracy theorist,” but I sometimes feel that we have made the language more complicated deliberately.

  4. Richard Holmes says:

    The Joint Chiefs of Staff are just regular guys.

    • says:

      Indeed you’ve identified an instance in which a singular “f” ending is not changed to a plural ending in “ves.” The reason for this is that the word chief was introduced to English from Old French sometime between 1100 A.D. and 1400 A.D. Words that are borrowed into English typically do not change in the same ways that native English words do.

  5. Jayden says:

    If the plural of goose is geese then why can’t the plural of moose be meese?

    Do you have any insight on how these plural nouns came to be?

    • says:

      While we haven’t researched the origins of all of the irregular plural nouns in English, we have noted that irregular plural nouns typically were formed from Old English words, many of which underwent sound changes over time. The word moose is considered a “newer” word, having been introduced to English from the native American Algonquin language around 1600 A.D. At first, the plural was mooses, a spelling that steadily faded in the 1800s until becoming obscure in the early 1900s, leaving us with the current plural, moose.

  6. Kristine Anderson says:

    The English language never ceases to amaze me. I’ve been a professional writer for more than 30 years and I still keep learning. That’s the beauty of it — I won’t get bored since I always need to study!

  7. PJ O'Malley says:

    Here in Arizona I feel comfortable saying cactuses. I believe cacti is a made-up word that has somehow caught on because it sounds so elitist. You might want to research this.

    • says:

      Both “cacti” and “cactuses” are standard, acceptable forms of the plural of “cactus.”

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