Here you will find our ESL activities and worksheets on irregular plural nouns. We are currently designing all new content and will post more worksheets as we create them. You can create a free account and we will update you when we release more content.

Recap

Irregular plural nouns are nouns that, unlike most nouns in English, cannot be converted to their plural form simply by suffixing with s or es.

Here is a list of the most common irregular nouns in English:

SingularPlural
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
chรขteauchรขteaux or chรขteaus
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