Irregular Plural Nouns | Grammar Rules, List & Examples

Learn the difference between plural and singular nouns; and different ways to form Irregular Plural Nouns in English with list and examples.

No Change in the Plural

Some nouns have identical singular and plural. Many of these are the names of animals.

  • 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
  • Offspring – offspring
  • 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):

  • 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

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

  • 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

  • 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 – polyhedra

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

 

2 responses on "Irregular Plural Nouns | Grammar Rules, List & Examples"

  1. Thank you. Some if the words are so simple that we tend to get confused, especially, the Latin words. My students are amazed.
    Thank you once again.

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