100 Irregular Plural Nouns in English

Examples of Irregular Plural Nouns in English
ThoughtCo./Melissa Ling

Most English nouns form their plural by adding either -s (books, bands, bells) or -es (boxes, bunches, batches). These plural forms are said to follow a regular pattern.

Irregular Plural Nouns

"The Penguin Writer's Manual"

"There are no easy rules, unfortunately, for irregular plurals in English. They simply have to be learnt and remembered."

Not all nouns conform to the standard pattern. In fact, some of the most common English nouns have irregular plural forms, such as woman/women and child/children.

In addition, several nouns have alternative plurals, one regular and the other irregular.

In regard to these alternative forms, there are no strict rules to guide our use of them.

"The Cambridge Encyclopedia of the English Language"

"People have to learn which form to use as they meet the words for the first time, and must become aware of variations in usage. When there is a choice, the classical [irregular] plural is usually the more technical, learned, or formal, as in the case of formulas vs. formulae or curriculums vs. curricula. Sometimes, alternative plurals have even developed different senses, as in the cases of (spirit) mediums vs. (mass) media, or appendixes (in bodies or books) vs. appendices (only in books)."

As you'll see in the list that follows, many words with irregular plurals are loanwords that have kept their foreign plural forms (or at least held on to those forms as alternatives to regular English plurals).

100 Irregular Plural Nouns List

In the list below, you'll find singular noun forms in the left column and the corresponding plural forms in the right column. When a noun has more than one plural form, the irregular one appears first, though that doesn't necessarily mean that the irregular form is more widely accepted than the regular form.

addendumaddenda or addendums
aircraftaircraft
alumnaalumnae
alumnusalumni
analysisanalyses
antennaantennae or antennas
antithesisantitheses
apexapices or apexes
appendixappendices or appendixes
axisaxes
bacillusbacilli
bacteriumbacteria
basisbases
beaubeaux or beaus
bisonbison
bureaubureaux or bureaus
cactuscacti or cactus or cactuses
châteauchâteaux or châteaus
childchildren
codexcodices
concertoconcerti or concertos
corpuscorpora
crisiscrises
criterioncriteria or criterions
curriculumcurricula or curriculums
datumdata
deerdeer or deers
diagnosisdiagnoses
diedice or dies
dwarfdwarves or dwarfs
ellipsisellipses
erratumerrata
faux pasfaux pas
fezfezzes or fezes
fishfish or fishes
focusfoci or focuses
footfeet or foot
formulaformulae or formulas
fungusfungi or funguses
genusgenera or genuses
goosegeese
graffitograffiti
grousegrouse or grouses
halfhalves
hoofhooves or hoofs
hypothesishypotheses
indexindices or indexes
larvalarvae or larvas
librettolibretti or librettos
loafloaves
locusloci
louselice
manmen
matrixmatrices or matrixes
mediummedia or mediums
memorandummemoranda or memorandums
minutiaminutiae
moosemoose
mousemice
nebulanebulae or nebulas
nucleusnuclei or nucleuses
oasisoases
offspringoffspring or offsprings
opusopera or opuses
ovumova
oxoxen or ox
parenthesisparentheses
phenomenonphenomena or phenomenons
phylumphyla
quizquizzes
radiusradii or radiuses
referendumreferenda or referendums
salmonsalmon or salmons
scarfscarves or scarfs
selfselves
seriesseries
sheepsheep
shrimpshrimp or shrimps
speciesspecies
stimulusstimuli
stratumstrata
swineswine
syllabussyllabi or syllabuses
symposiumsymposia or symposiums
synopsissynopses
tableautableaux or tableaus
thesistheses
thiefthieves
toothteeth
trouttrout or trouts
tunatuna or tunas
vertebravertebrae or vertebras
vertexvertices or vertexes
vitavitae
vortexvortices or vortexes
wharfwharves or wharfs
wifewives
wolfwolves
womanwomen

Sources

  • Crystal, David. "The Cambridge Encyclopedia of the English Language." 3rd Edition, Cambridge University Press, January 24, 2019.
  • Manser, Martin. "Penguin Writers Manual." Penguin Reference Books, Stephen Curtis, Paperback, International Edition, UK ed. edition, Penguin UK, August 24, 2004.