1.4: Irregular Plural Nouns

Last updated
Save as PDF

Page ID: 182771

SUNY/Lumen Learning
SUNY and Lumen Learning

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

Irregular plurals, unlike regular plurals, don’t necessarily follow any particular pattern—instead, they follow a lot of different patterns. Because of this, irregular plurals require a lot of memorization; you need to remember which nouns belong to which type of pluralization. Mastering irregulars uses a different region of your brain than regular pluralization: it’s an entirely different skill set than regular pluralization. So don’t get too frustrated if you can’t remember the correct plural. If you’re ever in doubt, the dictionary is there for you.

No Change (Base Plurals)

The first kind of irregular plural we’ll talk about is the no-change or base plural. In these words, the singular noun has the exact same form as the plural. Most no-change plurals are types of animals:

sheep
fish
deer
moose

Mid-Word Vowel Change

In a few words, the mid-word vowels are changed to form the plural. This video lists all seven of these words and their plurals.

Note: The plural for a computer mouse (as opposed to the fuzzy animal) can either be mice or mouses. Some people prefer mouses as it creates some differentiation between the two words.

Plural –en

And last we have plural –en. In these words –en is used as the plural ending instead of –s or -es.

child → children
ox → oxen
brother → brethren
sister → sistren

Note: Brethren and sistren are antiquated terms that you’re unlikely to run into in your life; however, since these are the only four words in English that use this plural, all four have been included above.

Practice

What are the correct plurals for the following words?

Singular	Plural	Singular	Plural
goose	[practice-area rows=”1″][/practice-area]	moose	[practice-area rows=”1″][/practice-area]
fish	[practice-area rows=”1″][/practice-area]	child	[practice-area rows=”1″][/practice-area]
man	[practice-area rows=”1″][/practice-area]	tooth	[practice-area rows=”1″][/practice-area]

[reveal-answer q=”245006″]Show Answer[/reveal-answer]
[hidden-answer a=”245006″]

Singular	Plural	Singular	Plural
goose	geese	moose	moose
fish	fish	child	children
man	men	tooth	teeth

[/hidden-answer]

Borrowed Words –i, –en, –a, –es, –ae

The last category of irregular plurals is borrowed words. These words are native to other languages (e.g., Latin, Greek) and have retained the pluralization rules from their original tongue.

Singular –us; Plural –i

cactus → cacti
fungus → fungi
syllabus → syllabi

In informal speech, cactuses and funguses are acceptable. Octopuses is preferred to octopi, and the ancient Greeks used the pluralization “octopodes.” The use of octopi is a common use of the plural form of the word “octopus.”

If you are in doubt, it’s a good practice to look up the word in a dictionary. Here are few other singular to plural forms of irregular nouns.

Singular -a; Plural –ae

formula → formulae (sometimes formulas)
vertebra → vertebrae
larva → larvae

Singular –ix, –ex; Plural –ices, –es

appendix → appendices (sometimes appendixes)
index → indices

Singular –on, –um; Plural –a

criterion → criteria
bacterium → bacteria
medium → media

Singular –is; Plural –es

analysis → analyses
crisis → crises
thesis → theses

Practice

What are the correct plurals for the following words?

Singular	Plural	Singular	Plural
memorandum	[practice-area rows=”1″][/practice-area]	emphasis	[practice-area rows=”1″][/practice-area]
focus	[practice-area rows=”1″][/practice-area]	basis	[practice-area rows=”1″][/practice-area]
nucleus	[practice-area rows=”1″][/practice-area]	phenomenon	[practice-area rows=”1″][/practice-area]
appendix	[practice-area rows=”1″][/practice-area]	curriculum	[practice-area rows=”1″][/practice-area]
parenthesis	[practice-area rows=”1″][/practice-area]	hypothesis	[practice-area rows=”1″][/practice-area]
stimulus	[practice-area rows=”1″][/practice-area]	vertebra	[practice-area rows=”1″][/practice-area]

[reveal-answer q=”245005″]Show Answer[/reveal-answer]
[hidden-answer a=”245005″]

Singular	Plural	Singular	Plural
memorandum	memoranda	emphasis	emphases
focus	foci (focuses is also acceptable)	basis	bases
nucleus	nuclei	phenomenon	phenomena
appendix	appendices (appendixes is also acceptable)	curriculum	curricula
parenthesis	parentheses	hypothesis	hypotheses
stimulus	stimuli	vertebra	vertebrae

[/hidden-answer]

Contributors and Attributions

Irregular Plural Nouns. Provided by: Lumen Learning. License: CC BY: Attribution

Irregular plural nouns - the MUTANT PLURALS. Authored by: David Rheinstrom. Provided by: Khan Academy. Located at: https://www.khanacademy.org/humanities/grammar/partsofspeech/grammar-nouns/v/irregular-plural-nouns-part-iv-the-parts-of-speech-grammar. License: CC BY-NC-SA: Attribution-NonCommercial-ShareAlike
Image of geese. Authored by: Sarah JOY. Provided by: The Noun Project. Located at: https://thenounproject.com/search/?q=geese&i=334679. License: CC BY: Attribution