Irregular Plural Nouns

While most plural nouns follow a standard rule of adding an “s” or “es” to the
end of the singular form, there are some irregular plural nouns that do not
follow this pattern. These nouns often have unique spellings and can be
challenging for language learners to master.

In this article, we will explore what irregular plural nouns are, how to form
them, and provide examples to help you better understand their usage. We
will also discuss common irregular plural noun patterns and provide tips for
identifying and using them correctly. Let’s uncover the mysteries of irregular
plural nouns together!

Examples of irregular nouns in singular and plural format:

Man- Men

Foot- Feet

Mouse- Mice

Child- Children

Woman Women
-

Goose- Geese

Person- People
Irregular Plural Nouns | Rules
No Change in the Plural
Some nouns have identical singular and plural. Many of these are the names
of animals.

Irregular Plural Nouns List:

 Aircraft – aircraft
 Barracks – barracks
 Deer – deer
 Gallows – gallows
 Moose – moose
 Salmon – salmon
 Hovercraft – hovercraft
 Spacecraft – spacecraft
 Series – series
 Species – species
 Means – means
 Offspring – offspring
 Deer – deer
 Fish – fish
 Sheep – sheep
 Trout – trout
 Swine – swine

Changing the Spelling of the Singular Noun

The plural is sometimes formed by simply changing the vowel sound of the
singular (these are sometimes called mutated plurals):

Irregular Plural Nouns List:

 Person – people
 Ox – oxen
  Man – men
 Woman – women
 Caveman – cavemen
 Policeman – policemen
 Child – children
 Tooth – teeth
 Foot – feet
 Goose – geese
 Mouse – mice
 Louse – lice
 Penny – pence

Note: There are many compounds of man and woman that form their plurals
in the same way: postmen, policewomen, etc.

Irregular Plural Nouns from Latin and Greek

Final a becomes -ae (also -æ), or just adds -s

 Alumna – alumnae
 Formula – formulae/formulas
 Antenna – antennae (for insects)/antennas (for electronic devices)
Final ex or ix becomes -ices

 Index – indices /indexes

 Matrix – matrices
 Vertex – vertices
 Appendix – appendices

Final is becomes es

 Axis – axes
 Genesis – geneses
 Nemesis – nemeses
 Crisis – crises
 Testis – testes
Final um becomes -a, or just adds -s

Irregular Plural Nouns List:

 Addendum – addenda
 Corrigendum – corrigenda
 Datum – data
 Forum – fora/forums
 Medium – media/ mediums
 Memorandum – memoranda/memorandums
 Millennium – millennia
 Ovum – ova
 Spectrum – spectra

Final us becomes -i or -era or -ora or just adds -es

Irregular Plural Nouns List:

 Alumnus – alumni
 Corpus – corpora
 Census – censuses
 Focus – foci
 Genus – genera
 Prospectus – prospectuses
 Radius – radii
 Campus – campuses
 Succubus – succubi
 Stylus – styli
 Syllabus – syllabi/syllabuses
 Viscus – viscera
 Virus – viruses/virii
 Cactus – cactuses/cacti
 Fungus – fungi
 Hippopotamus – hippopotamuses/hippopotami
 Octopus – octopuses
 Terminus – termini/terminuses
  Uterus – uteri/uteruses

Final us remains unchanged in the plural

 Meatus – meatus/meatuses
 Status – status/statuses

Final on becomes -a

 Automaton – automata
 Criterion – criteria
 Phenomenon – phenomena
 Polyhedron – polyhedral

Final as in one case changes to -antes

 Atlas – Atlantes (statues of the Titan); but Atlas – atlases (map

collections)

Final ma in nouns of Greek origin can become -mata

Final ma in nouns of Greek origin can become -mata, although -s is usually

also acceptable, and in many cases more common.

 Stigma – stigmata/stigmas
 Stoma – stomata/stomas
 Schema – schemata/schemas
 Dogma – dogmata/dogmas
 Lemma – lemmata/lemmas
 Anathema – anathemata/anathemas
Irregular Plural Nouns from Other Languages
Some nouns of French origin add an -x:

 Beau – beaux/beaus
 Bureau – bureaux/bureaus
 Tableau – tableaux/tableaus
Nouns of Slavic origin add -a or -i according to native rules, or just -s:

 Kniazhestvo – kniazhestva/kniazhestvos
 Kobzar – kobzari/kobzars
 Oblast – oblasti/oblasts
Nouns of Hebrew origin add -im or -ot (generally m/f) according to native
rules, or just -s:

Cherub – cherubim/cherubs

 Seraph – seraphim/seraphs
 Matzah – matzot/matzahs
 Kibbutz – kibbutzim/kibbutzes
Many nouns of Japanese origin have no plural form and do not change:

 Benshi – benshi
 Otaku – otaku
 Samurai – samurai
Nouns from languages other than the above generally form plurals as if they
were native English words:

 Canoe – canoes
 Igloo – igloos
 Kangaroo – kangaroos
 Kayak – kayaks
 Kindergarten – kindergartens
 Pizza – pizzas
 Sauna – saunas
 Ninja – ninjas
 Frequently Misused Irregular Plural Nouns
Irregular plural nouns are those that don’t follow the standard rule of adding -
s or -es to form their plural versions. This can often lead to confusion and
misuse in everyday writing and speech. This section will present a few widely
misused irregular plural nouns and provide their correct plural forms.

Man / Men and Woman / Women: One common mistake is

using mans or womans as plural forms, which is incorrect. The correct plurals
are men and women.

Child / Children: Similarly, the plural of child is not childs but children.

Mouse / Mice and Goose / Geese: It’s essential to remember that the plural
of mouse is mice, and the plural of goose is geese.

Tooth / Teeth and Foot / Feet: These nouns have plurals that are quite
different from their singular forms. The correct plurals are teeth and feet,
not tooths and foots.

Person / People: Though the irregular plural form is people, be aware that this
does not apply to all cases. The word persons is used in legal contexts or
specific situations involving a small number of individuals.

Here is a list of some other irregular plural nouns frequently misused:

Singular Correct Plural Incorrect Plural

Cactus Cacti Cactuses

Octopus Octopuses Octopi

Sheep Sheep Sheeps

 Singular Correct Plural Incorrect Plural

Ox Oxen Oxes