English Irregular Plural Nouns

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Lists adapted and compiled by:
Joanna Crump-- mailto:%20gs08jlc@panther.gsu.edu
Graduate student, Department of Applied Linguistics/ESL
Georgia State University
January 27, 1997

Regular Plural Forms

The majority of English count nouns are regular and predictable in the spelling of the plural form. Add -s to the end of the singular form or -es to those singulars that end in a sibilant sound (/s/, /z/, /ts/, /dz/).
 

-s -es
boy boys horse horses
bed beds edge edges
book books patch patches
pencil pencils prize prizes
day days box boxes
However, if the singular ends with -y and the -y is not preceded by a vowel (or is not a proper name) the -y changes to -i and the plural is then -es.
 
-y becomes -ies -y becomes -ys
spy spies osprey ospreys
poppy poppies bay bays
penny pennies Germany Germanys
Outside of this pattern, however, are several nouns which are irregular in their spelling. Below is a semi-comprehensive list compiled from various sources.
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Irregular Plural Nouns - List One

Some nouns that end in -f or -fe are changed to -ves in the plural:
 

-f or -fe becomes -ves
calf calves
elf elves
half halves
hoof hooves
knife knives
leaf leaves
life lives
loaf loaves
scarf scarfs/scarves
self selves
sheaf sheaves
shelf shelves
thief thieves
wife wives
wolf wolves
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Irregular Plural Nouns - List Two

Some nouns change the vowel sound in becoming plural:
 

singular plural
fireman firemen
foot feet
goose geese
louse lice
man men
mouse mice
tooth teeth
woman women
Some Old English plurals are still in use:
 
singular plural
child children
ox oxen
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Irregular Plural Nouns - List Three

Some nouns ending in -o take -s as the plural, while others take -es.
 

-o becomes -os -o becomes -oes
auto autos echo echoes
kangaroo kangaroos embargo embargoes
kilo kilos hero heroes
memo memos potato potatoes
photo photos tomato tomatoes
piano pianos torpedo torpedoes
pimento pimentos veto vetoes
pro pros
solo solos
soprano sopranos
studio studios
tattoo tattoos
video videos
zoo zoos
Some nouns ending in -o take either -s or -es:
 
singular plural
buffalo buffalos/buffaloes
cargo cargos/cargoes
halo halos/haloes
mosquito mosquitos/mosquitoes
motto mottos/mottoes
no nos/noes
tornado tornados/tornadoes
volcano volcanos/volcanoes
zero zeros/zeroes
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Irregular Plural Nouns - List Four

Some nouns do not change at all:
 

singular plural
cod* cod*
deer deer
fish* fish*
offspring offspring
perch* perch*
sheep sheep
trout* trout*
*Notice that these are names of fish. Many (but not all!) fish have irregular plural forms. Salmon, pike, halibut and tuna are further examples, but one shark becomes two sharks.

These include nouns that are traditionally plural, but are also used for singular forms:
 

singular plural
barracks barracks
crossroads crossroads
dice/die dice
gallows gallows
headquarters headquarters
means means
series series
species species
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Irregular Plural Nouns - List Five

Other nouns retain foreign plurals. Note that some of these have adapted a regular English plural form as well.
 

singular foreign plural English plural in use
alga algae
amoeba amoebae amoebas
antenna antennae antennas
formula formulae formulas
larva larvae
nebula nebulae nebulas
vertebra vertebrae
Nouns ending in -us with plural -a (only in technical use):
 
singular plural
corpus corpora
genus genera
Nouns ending in -us with plural -i:
 
singular foreign plural English plural in use
alumnus alumni
bacillus bacilli
cactus cacti cactuses
focus foci
fungus fungi funguses
nucleus nuclei
octopus octopi octopuses
radius radii
stimulus stimuli
syllabus syllabi syllabuses
terminus termini
Nouns ending in -um with plural -a:
 
singular Foreign plural  English plural in use
addendum addenda
bacterium bacteria
curriculum curricula curriculums
datum data
erratum errata
medium media
memorandum memoranda memorandums
ovum ova
stratum strata
symposium symposia symposiums
Nouns ending in -ex, -ix becoming plural -ices:
 
singular Foreign plural  English plural in use
apex apices apexes
appendix appendices appendixes
cervix cervices cervixes
index indices indexes
matrix matrices matrixes
vortex vortices
Nouns ending in -is becoming -es in plural:
 
singular plural
analysis analyses
axis axes
basis bases
crisis crises
diagnosis diagnoses
emphasis emphases
hypothesis hypotheses
neurosis neuroses
oasis oases
parenthesis parentheses
synopsis synopses
thesis theses
Nouns ending in -on becoming -a:
 
singular plural
criterion criteria
phenomenon phenomena
automaton automata
Other irregular plurals, retained from different languages:
 
singular plural
Italian libretto libretti
tempo tempi
virtuoso virtuosi
Hebrew cherub cherubim
seraph seraphim
Greek schema schemata
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References
Azar, B.S. (1983). Chartbook: A reference grammar. (2nd ed.). Englewood Cliffs, NJ:
Prentice Hall Regents.
Byrd, P. and Benson, B. (1994). Problem/solution: A reference for ESL writers. 
Boston: Heinle & Heinle.
Greenbaum, S. and Quirk, R. (1900). A student's grammar of the English language.
Essex: Longman Group UK Limited.
Hodges, J.C. and Whitten, M.E. (Eds.). (1986). Harbrace college handbook (10th ed.).
San Diego: Harcourt Brace Jovanovich.
Maclin, A. (1987). Reference guide to English: A handbook of English as a second language
(2nd ed.). New York: Holt, Rinehart & Winston.
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Other Useful Links:

English Grammar on the Web
Journal of English Grammar on the Web
Susan Jones' List of Irregular Plurals
Lists of Grammar Lists
Georgia State University