A List of 100 Irregular Plural Nouns in English

Wolves on a rock
The plural form of wolf is wolves. Guy Edwardes/Getty Images
There are no easy rules, unfortunately, for irregular plurals in English. They simply have to be learnt and remembered.
(S. Curtis and M. Manser, The Penguin Writer's Manual, 2002)

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.

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

(The reasons for this are briefly discussed in the article Plural Forms of English Nouns.) 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:

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).
(David Crystal, The Cambridge Encyclopedia of the English Language, 2nd ed. Cambridge University Press, 2003)

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).

List of 100 Irregular Plural Nouns in English

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.

SOURCES: The plural forms in this list are recognized by Merriam-Webster's Collegiate Dictionary (2003) and The American Heritage Dictionary of the English Language (2011).

 

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
prognosisprognoses
  
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

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Nordquist, Richard. "A List of 100 Irregular Plural Nouns in English." ThoughtCo, Sep. 21, 2017, thoughtco.com/irregular-plural-nouns-in-english-1692634. Nordquist, Richard. (2017, September 21). A List of 100 Irregular Plural Nouns in English. Retrieved from https://www.thoughtco.com/irregular-plural-nouns-in-english-1692634 Nordquist, Richard. "A List of 100 Irregular Plural Nouns in English." ThoughtCo. https://www.thoughtco.com/irregular-plural-nouns-in-english-1692634 (accessed November 21, 2017).