A Long List of Irregular Plural Nouns

Usually it is very easy to make plural nouns from singular nouns by following some standard rules such as adding -s or -es to the end of the word. However, there are some nouns that don’t seem to follow the rules. Such nouns are called irregular nouns. That means they don’t become plural the “regular” way.

Here is a list of those irregular plural nouns.

Irregular plural nouns that replace end letter ‘f’ & ‘fe’ with ves:

Singular: Plural:

calf calves

elf elves

knife knives

leaf leaves

loaf loaves

shelf shelves

wolf wolves

Irregular plural nouns made by changing vowels also called Apophonic plurals:

Singular: Plural:

analysis analyses

dormouse dormice

foot feet

goose geese

louse lice

man men

mouse mice

neurosis neuroses

oasis oases

tooth teeth

thesis theses

woman women

Irregular plural nouns made by changing the word, or adding a different ending:

Singular: Plural:

abyss abysses

alumnus alumni

Appendix appendices

aquarium aquaria

bacterium bacteria

cactus cacti

château chateaux

child children

ox oxen

Irregular plural nouns that have the same spelling as their singular form (most of them are animals):

Singular: Plural:

Bison Bison

Buffalo buffalo

Deer deer

Duck duck

Pants Pants

Pike pike

Salmon salmon

Scissors scissors

series series

Sheep sheep

Squid squid

Swine swine

Trout trout

Animal nouns that become plural by keeping the same spelling as the singular form or by adding an -s or -es.

Singular: Plural:

cod cod or cods

fish fish or fishes

hoax hoax or hoaxes

quail quail or quails

shrimp shrimp or shrimps

Singular: Plural:

index indexes

moose moose

mouse mice

nucleus nuclei

octopus octopi

person people

plateau plateaux

runner-up runners-up

son-in-law sons-in-law

species species

waltz waltzes

Irregular plural nouns that replace end word -a with -ae or -s:

Singular: Plural:

alumna alumnae

Encyclopaedia encyclopædia

Encyclopedia encyclopaedias / encyclopedias

formula formulae/formulas

Irregular plural nouns that replace end word -ex or -ix with -ices or just adds -es:

Singular: Plural:

index indices or indexes

matrix matrices

vertex vertices

Irregular plural nouns that replace end word -is with -es:

Singular: Plural:

axis axes

crisis crises

emphasis emphases

nemesis nemeses

testis testes

Irregular plural nouns that replace end word -is with -es:

Singular: Plural:

series series

species species

Irregular plural nouns that replace end word -um with -a:

Singular: Plural:

Addendum addenda

agendum agenda or agendas

corrigendum corrigenda

datum data

forum fora/forums

medium media or mediums

memorandum memoranda/memorandums

millennium millennia

ovum ova

spectrum spectra

Irregular plural nouns that replace end word -us with -i or -era or -ora, or just adds -es:

Singular: Plural:

Alumnus alumni

campus campuses or campi

census censuses

circus circuses

corpus corpora

curriculum curricula

focus foci

fungus fungi

genus genera

hippopotamus hippopotami/ hippopotamuses

meatus meatus/meatuses

octopus octopuses octopi/ octopodes

prospectus prospectuses

platypus platypuses / platypodes

radius radii

status status/ statuses

stylus styli

syllabus syllabi

succubus succubi

terminus termini/terminuses

uterus uteri/uteruses

virus viruses

viscus viscera

Irregular plural nouns that replace end word –on with –a:

Singular: Plural:

automaton automata

criterion criteria

phenomenon phenomena

polyhedron polyhedral

Irregular plural nouns that replace end word –as with –ntes and -es:

Singular: Plural:

Atlas Atlantes (it is for the statues of the Titan)

atlas atlases (map collections)

Irregular plural nouns that replace end word –ma with -mata or -s:

Singular: Plural:

Anathema anathemata or anathemas

dogma dogmata or dogmas

lemma lemmata or lemmas

schema schemata or schemas

stigma stigmata or stigmas

stoma stomata or stomas

Irregular plural nouns made by adding -x or -s (These words are mostly of different language):

Singular: Plural:

beau beaux or beaus

bureau bureaux or bureaus

château châteaux or châteaus

tableau tableaux or tableaus

Irregular Plurals of compound nouns:

Singular: Plural:

attorney general attorneys general

chief of staff chiefs of staff

court martial courts martial

director general directors general

governor-general governors-general

head banger head bangers

minister-president ministers-president

passerby passersby

seaman seamen

ship of the line ships of the line

son-in-law sons-in-law

Irregular Plurals of compound nouns with two heads:

Singular: Plural:

man-child men-children

manservant menservants

woman doctor women doctors

Irregular Plurals of compound nouns with two heads, but only the final head will be pluralize:

Singular: Plural:

brigadier general brigadier generals

city-state city-states

major general major generals

nurse-practitioner nurse-practitioners

scholar-poet scholar-poets

Irregular Plurals of compound nouns with three or more words, a term functioning as a head, only that term is pluralized:

Singular: Plural:

man-about-town men-about-town

man-of-war men-of-war

woman of the street women of the street\

Irregular Plurals of compound nouns with three or more words, a term functioning as a head is in the beginning and at the end, either term can be pluralized:

Singular: Plural:

ham on rye hams on rye or ham-on-ryes

jack-in-the-box jacks-in-the-box or jack-in-the-boxes

jack-in-the-pulpit jacks-in-the-pulpit or jack-in-the-pulpits

Few extended compounds, both the terms may be pluralized:

Singular: Plural:

head of state heads of states/heads of state

son of a bitch sons of bitches/sons-of-a-bitch

Besides, there are additional plural nouns whose singular forms exist, but hardly their plurals are used, like:

Singular: Plural:

nuptial nuptials

phalanx phalanges

tiding tidings

victual victuals

viscus viscera

Thanks for reading! Hope this list helps!!