Prototypical English nouns have both singular and plural forms. Singular nouns refer to one “person, place, thing, or idea” while plural nouns refer to “not one” (two or more or less than one) “people, places, things, or ideas.” Regular nouns are predictable, taking an -s suffix to form the plural. Irregular nouns are unpredictable, following other rules to form the plural. Learn how to form the plural forms of irregular English nouns with the following guide.
Forming Irregular Plural Nouns
Unlike most English nouns through which -s or -es suffixation creates the plural forms, irregular English nouns require different changes from the singular to the plural. Some irregular English nouns require a vowel sound change, or ablaut, between the singular and plural forms. For example:
- foot – feet
- goose – geese
- louse – lice
- man – men
- mouse – mice
- person – people (vowel and consonant sound changes)
- tooth – teeth
- woman – women
Some irregular nouns in English are formed by the addition of an -en suffix. For example:
- child – children
- ox – oxen
- hose – hosen (archaic)
- brother – brethren (archaic)
For other irregular English nouns, the plural form is identical to the singular form. For example:
- bison
- deer
- fish
- moose
- offspring
- sheep
Forming Foreign Loanword Plurals
Many loanwords from foreign languages have irregular plural forms. For Latin loanwords that end in a, change the a to an ae. For example:
- alumna – alumnae
- formula – formulae
For Latin loanwords that end in ex or ix, change the ex or ix to ices. For example:
- index – indices/indexes
- matrix – matrices
- vertex – vertices
For Latin loanwords that end in is, change the is to an es. For example:
- analysis – analyses
- axis – axes
- crisis – crises
- testis – testes
- thesis – theses
For Latin loanwords that end in on, change the on to an a. For example:
- automaton – automata
- criterion – criteria
- phenomenon – phenomena
For Latin loanwords that end in um, change the um to an a. For example:
- addendum – addenda
- datum – data
- medium – media
- memorandum – memoranda
- millennium – millennia
For Latin loanwords that end in us, change the us to an i, era, ora, or es. For example:
- alumnus – alumni
- cactus – cacti
- corpus – corpora
- census – censuses
- focus – foci
- fungus – fungi
- genus – genera
- radius – radii
- syllabus – syllabi
- uterus – uteri
- viscus – viscera
For Greek loanwords that end in ma, add the suffix -ta to the end of the word. For example:
- dogma – dogmata
- schema – schemata
- stigma – stigmata
- stoma – stomata
For some French loanwords that end in eau, add a silent -x suffix to the end of the word. For example:
- beau – beaux
- bureau – bureaux/bureaus
- château – châteaux
For some Hebrew loanwords, add the suffix -im or -ot to the end of the word. For example:
- cherub – cherubim
- matzah – matzot
- seraph – seraphim
Irregular English nouns regular either stem changes or ending changes (or sometimes both) in the plural. Loanwords from foreign languages also often have irregular plural forms depending on the language from which the noun was borrowed.
Learn about forming the plurals of regular English nouns in Regular Plural Nouns in English.
See also Plural English Nouns for a printable that lists the rules for forming plurals of regular, irregular, and foreign loanword nouns in the English language with examples.
References
Hopper, Paul J. 1999. A short course in grammar. New York: W. W. Norton & Company.
Huddleston, Rodney. 1984. Introduction to the grammar of English. Cambridge: Cambridge University Press.
