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Irregular Plural Nouns

A list of all irregular plural noun form in the English language, for you convenience and ease of reference.



Regular vs. irregular nouns

In English, we tend to like to define things by kind or type. Similar to how regular and irregular verbs are categorized by the use of -ed in the past tense, nouns have their own way to separate between regular and irregular. The difference between regular and irregular nouns is this:


  • Regular nouns end in -s / -es in their plural forms.


  • Irregular nouns end in something other than -s / -es in their plural forms.



When it comes to nouns, we obviously aren’t speaking about the change a noun goes through in tense, since nouns have no tense. Instead, it’s how a noun changes in its form to mean one thing (or person, place), or more than one thing/person/place (e.g., the change from singular to plural). By and large, the majority of English nouns use the conventional -s or -es to indicate a plural:


  • dog ➜ dogs
  • cat ➜ cats
  • table ➜ tables
  • fox ➜ foxes
  • tomato ➜ tomatoes



These are regular nouns since they add s/es as a plural. As you can see from the list above, some just add an s, where others add es. When should you use s or es? And what do irregular nouns end in if not s/es? This will be answered, and we’ve also written out a list in this article of each of the irregular plural nouns in English, for your convenience and use.



Regular noun endings

Most nouns will just add n -s. However, we add es to singular nouns that end in –s, –ss, –sh, –ch, –z and sometimes -o; as in:


  • dress ➜ dresses
  • ash ➜ ashes
  • bench ➜ benches
  • box ➜ boxes
  • tomato ➜ tomatoes
  • quiz ➜ quizzes



Notice how some of the nouns above that end in “z” or “s” adds a double “z” or “s” before “es” (this is the correct form for nouns ending in “z” or “s”). With nouns that end in “y” as a singular, we replace the “y” with “ies” as a plural:

  • puppy ➜ puppies
  • baby ➜ babies



If the letter before the “y” is a vowel and not a consonant, add “s’ (not “ies”; e.g., ray/raysboy/boys). Most nouns that end in “ff”, “f” or “ef” add “s” as a plural, but some nouns that end in “f” or “fe” add “ves” as a plural. See the difference:


  • belief ➜ beliefs
  • cliff ➜ cliffs
  • chief ➜ chiefs
  • roof ➜ roofs
  • chef ➜ chefs


Whereas other nouns ending in “f” or “fe” add “ves” as a plural:


  • wolf ➜ wolves
  • calf ➜ calves
  • knife ➜ knives
  • wive ➜ wives



Singular nouns that end in “o” usually add “es” as a plural, but not always. Some will just add “s”, others “es”, and (this part gets really whacky) with some nouns, you can use either “s” or “es”. The options are practically endless. Take a look:

  • tomato ➜ tomatoes
  • potato ➜ potatoes
  • volcano ➜ volcanoes (or volcanos)
  • mango ➜ mangoes (or mangos)



These nouns that end in “o” just add “s”:

  • video ➜ videos
  • photo ➜ photos
  • halo ➜ halos



Irregular noun patterns

By looking at them, it appears like irregular plurals follow no rules, but if you look closely, you’ll see patterns that makes learning them much easier. Apologies for the repetitiveness, but just like when it comes to learning irregular verb forms, recognizing the patterns amongst their irregular-ness is an extremely effective way to remember them (I encourage it). Let’s get into the nuts and bolts of these ostensibly irregular nouns.



Some nouns add -en, or swap their inner vowels with another pair of vowels:

These nouns add -en:

  • child ➜ children
  • ox ➜ oxen



These nouns swap their inner vowels:

  • woman ➜ women
  • man ➜ men
  • person ➜ people
  • mouse ➜ mice



These swap their inner vowels of double o’s with e’s:

  • goose ➜ geese
  • tooth ➜ teeth
  • foot ➜ feet



Side-note: don’t get confusedjust because goose is geese plural, doesn’t mean moose becomes meese!

Nouns that end in -sis usually switch to ses as a plural:

  • synopsis ➜ synopses
  • crisis ➜ crises
  • oasis ➜ oases



Latin nouns that end in -um switch to -a:

  • memorandum ➜ memoranda
  • curriculum ➜ curricula
  • colloquium ➜ colloquia



Latin nouns that end in -ix switch to -ces/-xes:

  • matrix ➜ matrices/matrixes
  • apex ➜ apices/apexes
  • index ➜ indices/indexes



Some nouns don’t change at all from singular to plural:

  • sheep ➜ sheep
  • deer ➜ deer
  • aircraft ➜ aircraft

A mass noun names something we cannot physically count, or things that exist in a form which cannot be counted, either because they are abstract or too numerous to count. Because of this, abstract or mass nouns stay singular in form. Some examples are:

  • water
  • oil
  • sand
  • art



A comprehensive list of irregular nouns in English

SingularPlural
citycities
babybabies
ponyponies
oasisoases
diagnosisdiagnoses
synthesissyntheses
thesistheses
paralysisparalyses
psychosispsychoses
synopsissynopses
analysisanalyses
crisiscrises
hypothesishypotheses
prognosisprognosis
basisbases
ellipsisellipses
parenthesisparentheses
goosegeese
footfeet
toothteeth
childchildren
manmen
womanwomen
personpeople
oxoxen
diedice
louselice
mousemice
fungusfungi/fungasses
octopusoctopi/octopuses
syllabussyllabi/syllabuses
stimulusstimuli/stimuluses
alumnusalumni
platypusplatypi/platypuses
locusloci/locuses
radiusradii/radiuses
focusfoci/focuses
larvalarvae/larvas
genusgenera/genuses
datumdata
bacteriumbacteria
criterioncriteria
mediummedia
addendumaddenda/addendums
referendumreferenda/referendums
memorandummemoranda/memorandums
symposiumsymposia/symposiums
colloquiumcolloquia/colloquiums
phenomenonphenomena/phenomenons
spectrumspectra/spectrums
curriculumcurricula/curriculums
indexindices/indexes
shelfshelves
elfelves
knifeknives
lifelives
selfselves
wifewives
wolfwolves
calfcalves
halfhalves
bisonbison
cactuscacti/cactuses
scarfscarves
shrimpshrimp
moosemoose
deerdeer
sheepsheep
fishfish
tomatotomatoes
potatopotatoes
heroheroes
echoechoes
volcanovolcanoes
zerozeroes
appendixappendices/appendixes
axisaxes
apexapices/apexes
matrixmatrices/matrixes
vortexvortices/vortexes
vertexvertices/vortexes
A list of all the irregular nouns in English.



Sources

  1. Irregular Plurality


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