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!!
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