Irregular Plural Nouns - Confusing, Difficult Grammar Words

So Many Exceptions with Plurals

Mouse = Mice, so House = Hice?

Tooth = Teeth, so Booth = Beeth?

Dish = Dishes, so Fish = Fishes?

Regular nouns form plurals with "-s" or "-es."

While most plural nouns form their plurals with “s” or “es,” there are many that form the plural with a different spelling on the end. I'm not talking about plurals like feet, teeth, geese, mice, children, or any other commonly used irregular plurals. I'm talking about ones that are hard to remember--at least for me--and sound funny to the ears. Even as an English teacher, with a Master's in the subject, I don’t use these irregular plurals often, and I don’t hear them often. However, if you ever have to write a report, an article, or academic paper, you should use the correct plural. And if you need to make a speech in front of people, well, you should use the proper plural even if most of your audience would never use the irregular plural. At least, they should be impressed that you do!

While it might be more fun to spit out the plural of “hypothesis” as “hypothesises,” that isn’t the correct plural. There’s probably a reason for that, as it sounds really funny. Some more common words I hear with irregular plurals are:

Plurals that change "i" to "e"

 
 
analysis
analyses
crisis
crises
diagnosis
diagnoses
hypothesis
hypotheses
parenthesis
parentheses
Note: With the plural form, instead of the short "i" sound, the plural with the "e" is pronounced as the long e: "ee."

Nouns whose Plural Changes "us" to "i"

cactus
cacti
focus
foci
nucleus
nuclei
stimulus
simuli
 
 
Note: All of the examples in these charts are just a few of the many irregular plurals of this type.

Irregular Plurals that end in -a or -ia

bacterium
bacteria
criterion
criteria
memorandum
memoranda
phenomenon
phenomena
All of those plurals end in “a,” although “criterions” and “memorandums” are also correct. Then why even have the irregular form?

Other Confusing Irregular Plurals

The plural of “alumna” is “alumnae” if the alumna is female. A male “alumnus” becomes plural “alumni.” I can’t seem to keep that one in my head! Here’s a common word: data. Although “data” is thought by many to be both the singular and plural, “datum” is technically the singular form. And has anyone ever heard the plural of “formula” to be “formulae”? Neither have I. I’m sticking with “formulas,” which is also accepted. “Appendix” becomes “appendices.” The plural of “syllabus” is “syllabi,” although syllabuses (can you believe this?) is also accepted. Syllabuses. Now that is fun to say! I’m going with it.

I know I haven't hit all the irregular plurals. Consider how life turns to lives and knife to knives. Child becomes children, and man and woman become men and women. But we are more familiar with those, so I hope this article has been helpful in helping you with the most irregular of irregular plural nouns. Check out my other grammar hubs if you'd like. I'd love to see you there!

Poll: Feedback on Irregular Plural Nouns Lesson

Were you familiar with most of these irregular plural noun forms?

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Comments 51 comments

Sunshine625 profile image

Sunshine625 4 years ago from Orlando, FL

I've missed my Grammar Geek hubs!! Thanks teach! I learn so much from you:))


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

Aw, Sunshine, you're such an excellent student. I do need to do more grammar hubs. I have been jotting down ideas. You'll see more! I just get distracted with writing other things, too. Thanks so much for checking this one out! :-)


homesteadbound profile image

homesteadbound 4 years ago from Texas

Another great grammar hub! We all can use these great refreshers! They provide great stimuli! Thanks for SHARING!


Vinaya Ghimire profile image

Vinaya Ghimire 4 years ago from Nepal

I'm going to bookmark this hub for future reference.


healthwriterbob profile image

healthwriterbob 4 years ago from United States

Hi Victoria Lynn,

Once again you have entertained me with your hub. I just wanted to mention that it is the Latin language that gives us the plural of nouns like alumna, alumnus and datum. Although Latin is not spoken any more, it can still be useful for writers to have some knowledge of this language. Voted up and interesting. Take care.

Healthwriterbob


alocsin profile image

alocsin 4 years ago from Orange County, CA

An excellent hub for word lovers. Another source of confusion is using the wrong verb with some of these nouns. Voting this Up and Interesting.


ThePracticalMommy profile image

ThePracticalMommy 4 years ago from United States

I loved teaching this to my middle schoolers. They liked to make irregular changes to all sorts of words after that lesson; it was Language 'Arts' after all, and they were being 'artistic' with their words, they'd argue. :)

In our doctor's office, there is a shelf that is covered with a variety of cacti. My three year old was saying to me "Mama, look at all of the cactuses!". I said "Yep, there are a lot of cacti up there". He giggled at me and told me to stop making up silly words. ;)

Great hub! Voted up and sharing!


tammyswallow profile image

tammyswallow 4 years ago from North Carolina

One that I think is funny is octopus to octopi. We never hear people using this word. This is a very fun and interesting hub. It makes a good demonstration as to how hard English must be to learn for others. I always wonder what they think of this sentence: "I can't stand you." Poor foreigners and English students! You made it very fun to learn and this was a great refresher course. Thanks!


sholland10 profile image

sholland10 4 years ago from Southwest Missouri

Great grammar advice!! Voted and sharing! :-)


jeyaramd profile image

jeyaramd 4 years ago from Mississauga, Ontario

Its easy to confuse plural forms and grammar. Reading books helps make sense out of grammar. Sometimes, I feel I know that something is just not right. However, knowing the exact rules that the mistake pertains to is another story. Thanks for sharing this wonderful hub on grammar.


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

Thanks, homesteadbound! Glad it helps! I love grammar!!!!


Angela Biggs profile image

Angela Biggs 4 years ago from United Kingdom

It usually happens that you start writing and gets stuck at some point thinking about certain word. You just keep thinking and you don't find it right. I will keep these words in mind!!


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

Excellent, Vinaya. Hope it's helpful!


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

healthwriterbob--I love language and its origin. I've always wanted to take a Latin class. Perhaps I still will. Thanks for the great comments. I'm glad I entertained you! Awesome!


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

alocsin--I DO love words. You're right about the confusion in choosing the correct verb. Thanks for the great comments!


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

That's funny, PracticalMommy! Some of those plurals really do sound like made-up words. I love what you said about "language arts." I think that language IS an art!


arusho profile image

arusho 4 years ago from University Place, Wa.

Oooh, I will have to pick your brain, since you have revealed you are a master of the English language! I'm familiar with most of the irregular plural nouns, but it is so confusing sometimes that I just guess as to what I'm supposed to use. Grammar is confusing too, like when do you use are or is when it's a plural? Anyway, great hub!!


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

tammy--Yes, the English language is so hard for people to learn. I love your octupus to octupi. Fun and weird to say! I may have to add that to my hub!


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

thanks, sholland for reading, voting, and sharing!


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

jeyaramd--I've always felt that reading helps one to get better at language, such as spelling and grammar. Thanks for the great comments!

Angela--glad you enjoyed the hub!


imamkrate profile image

imamkrate 4 years ago from Dubai

thanks Victoria for this hub my dream is to study master of English


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

arusho--You can pick my brain anytime. I love grammar! And you've given me an idea for a grammar hub. Is vs. Are. Be looking for it. Thanks!


DzyMsLizzy profile image

DzyMsLizzy 4 years ago from Oakley, CA

Excellent! And leave us not forget datum/data; or nebula/nebulae. Ah--I think I just got an idea for my next hub--taking of on a spoof involving fictional characters with tricky names.

Wonderful! Voted up, awesome, interesting, useful and shared.


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

imamkrate--I'm happy to hear about your aspirations in English. I love language!


homesteadbound profile image

homesteadbound 4 years ago from Texas

While I was writing on nebulae, I found it could also be spelled nebulas. And when writing about octopi, it could also be spelled octopuses.


DzyMsLizzy profile image

DzyMsLizzy 4 years ago from Oakley, CA

**ack!** and note to self--don't make comments when feeling less than 100%, or you make stupid typos you don't catch until it's too late. I meant, of course, to say "...taking OFF on a spoof...." ..grrr.. Well, I have written that article, anyway. LOL


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

DzyMsLizzy! Yes, more good examples! Thanks for all the votes. And you've already written the spoof? I'll have to look for it!


DzyMsLizzy profile image

DzyMsLizzy 4 years ago from Oakley, CA

Thank you so much for the link!


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

homesteadbound--Octupuses AND octupi sound funny! haha

DzyMsLizzy--you're welcome about the link!


PDXKaraokeGuy profile image

PDXKaraokeGuy 4 years ago from Portland, Oregon

very good and useful hub, Vicki!


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

Thanks, PDX! I do want my grammar hubs to be useful. I appreciate the feedback!


Made profile image

Made 4 years ago from Finland

What an interesting hub! I really learned something here. I just remember learning "crisis - crises" in school. I guess I have much yet to learn about the English language.


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

Made--There's always so much to learn about English. I'm glad you found this hub helpful!


PDXKaraokeGuy profile image

PDXKaraokeGuy 4 years ago from Portland, Oregon

of course, Victoria. I just spent the last three days editing for a client who had no concept of grammar beyond it's existence. application was beyond him...


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

Oh my, PDX! You've had your work cut out for you, huh? :-)


PDXKaraokeGuy profile image

PDXKaraokeGuy 4 years ago from Portland, Oregon

ya, i sure did... and I undercharged him


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

haha, PDX. I guess we do what we've gotta do, huh? :-)


busyguru profile image

busyguru 4 years ago from U.S.

The English language is full of funky rules. I love your Hub for making sense out of nonsense.


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

Thanks, busyguru. I love how you put things!


Steve 4 years ago

Well, I admire the valuable information you offer in your articles.


Victoria Lynn profile image

Victoria Lynn 4 years ago from Arkansas, USA Author

Thanks, Steve! Much appreciated!


DamianOB 3 years ago

Hi Victoria. Your readers who are interested in this post may like to have a look at my book, If Houses Why Not Mouses? It explains the background to a lot of apparent irregularities in English. All the best, Damian O'Brien


Victoria Lynn profile image

Victoria Lynn 3 years ago from Arkansas, USA Author

Damian--I've wondered the same thing about houses and mouses! What about geese and meese/meece? I love the English language and its irregularities! (Sort of!) Thanks for the comments.


DamianOB 3 years ago

The book looks at the word goose as well, and shows how you can apply a series of sound change rules to turn it into the Sanskrit equivalent hansa. Here's the deal - we've got several words here which were all originally different, and for different reasons have at various stages of development have come to resemble each other. So, in Old English there was hus (house) and mus (mouse) , both pronounced with an -oo- sound. But the plural of hus was hus - the same form - because it was a neuter noun and these didn't change. Several centuries later, as the language simplified, hus adopted the regular s plural ending which gives us houses. But mus had a plural mys (the forerunner of mice), which in the pre-Old English period was musi. By the time of Old English the final i had merged with the u to produce y. Both hus and mus, and mys, then changed their vowels in the Great Vowel Shift to the sounds now used in mouse, house and mice. The spelling changed as well to reflect the new pronunciation. But goose wasn't pronounced like mus and hus in Old English. The word was gos. Just as mice comes from Old English mys which came from and older musi, so geese comes from Old English ges which came from an older form where, like mus-i and mys, a final i merged with the main vowel to produce ges. But then we have to look more deeply at it. Although the earlier plural of mus was musi, the original plural of gos was not gosi. By the time the word gos arrived in Old English it had undergone another change. Remember how I said that goose is related to the Sanskrit hansa? Originally, gos was actually gans (like hans-a), so you can see where the feminine gan-der comes from. There's more about this in my book. As for the moose and the mongoose, these aren't European animals or European words so they haven't been subject to the same patterns of development. I hope that's clear! As for octopus, I think people should say whatever they like for the plural. But if historical exactitude is your thing, it shouldn't be octopi. The us/i change as in syllabus/syllabi is for second declension Latin nouns. Octopus is third declension, and the plural reflects the Greek - octopodes. And not many people say that! All the best, Damian


DzyMsLizzy profile image

DzyMsLizzy 3 years ago from Oakley, CA

I return, reminded of the tale of a fellow with a small menagerie, and he wanted to have a mongoose. He wrote several drafts of a letter to the supplier, trying to get the plural right. "Dear sirs, please send me a pair of mongooses." ...no..... "Dear sirs, please send me a pair of mongeese." Um... maybe not... finally ending up with, "Dear sirs, please send me a mongoose, and by the way, please send another."


Victoria Lynn profile image

Victoria Lynn 3 years ago from Arkansas, USA Author

Damian--Octopodes sounds cool. My, how intricate and interesting. The history of words is fascinating to me, though a bit confusing. LOL. Thanks for sharing all that!


Victoria Lynn profile image

Victoria Lynn 3 years ago from Arkansas, USA Author

DzyMsLizzy--That is hilarious! And a perfect way around it!


Melovy profile image

Melovy 3 years ago from UK

Oddly, I did know about formulae, but not about foci. Possibly that's because I've rarely been able to put my focus on more than one thing at a time. :) I did not know that alumnae was was the plural of alumna, or even that the latter was a word. From now on, when I get invitations to my college alumni events I'll know that I'm not really invited at all, since it's just for the men! :) I don't think I've ever seen alumna used in the UK. Is it used in the States?

An interesting hub!


Victoria Lynn profile image

Victoria Lynn 3 years ago from Arkansas, USA Author

Melovy--It just struck me that it seems I've only heard "alumnus" rather than "alumna" for a female in the States. I guess it's all about the men here, too. LOL. Thanks for the comments!


AnWulf profile image

AnWulf 2 years ago

Foreign words which hav come into everyday English note often hav two plurals, the wonted English style and the foreign style (often from Latin or Greek). The English plural is always correct, but sometimes the foreign plural is better lik'd by some (wontedly by the ones that speak that tung). For byspel, focus can be either focuses or foci; udarnik can be either udarniks or udarniki (Russian).

Many Latin and Greek words hav kept their Latin/Greek plurals while many hav yielded to being English'd ... and more will yield as fewer folks study Latin/Greek. Truly, aside from when the English plural might make a word hard to say, there is no good reason to keep the foreign plural.

In Old English, there were many "strong" plurals that ended in -n. While most of these hav switcht over to an 's' ... the old ones may still be found: shoon (pl of shoe), eyen (pl of eye), kneen, treen, hosen, housen. An odd one is aurochsen.

Let's not leav out brethren and sistren. And one that folks sometimes mess up when they mean to say kith and kin; they'll say, wrongly, kine and kin. What's kine? It's the plural of cow (often noted for big groops of cows rather than the word cattle which is another word, not kin to cow.)

There there are new ones like boxen (pl of box) often found in techno-speak but it has slippt out and is sometimes found outside of talking about computers. If you recall the old VAX computer, the plural was often VAXen. The plural is unix can be unixen.


Victoria Lynn profile image

Victoria Lynn 2 years ago from Arkansas, USA Author

AnWulf--Thanks for the great comments! Language and how it evolves is so fascinating to me. It's so cool. Thank you so much for taking the time to share what you know. I love it!

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