Irregular plural nouns

  • In English, there are hundreds of nouns that don’t follow the standard rules for pluralization. There are no easy ways to remember them, so they generally have to be memorized.


    Some of the rarer irregular plurals are often misused, leading to the creation of variant forms, which usually encounter resistance at first but eventually make it into the language. For example, the plural of formula has traditionally been formulae, but formulas is now far more common, and few would call it incorrect.

    Latinate plurals

    Some nouns have retained their plural forms from Latin and other languages:

    singular plural
    addendum addenda
    alga algae
    alumnus alumni
    amoeba amoebae
    antenna antennae
    bacterium bacteria
    cactus cacti
    curriculum curricula
    datum data
    fungus fungi
    genus genera
    larva larvae
    memorandum memoranda
    stimulus stimuli
    syllabus syllabi
    vertebra vertebrae

    -o becoming –oes

    Most nouns ending in –o are pluralized by adding an –s, but some take –es instead—for example:

    singular plural
    echo echoes
    embargo embargoes
    hero heroes
    potato potatoes
    tomato tomatoes
    torpedo torpedoes
    veto vetoes

    Changing vowel sounds

    Some nouns change their central vowel sounds when pluralized—for example:

    singular plural
    foot feet
    goose geese
    louse lice
    man men
    mouse mice
    tooth teeth
    woman women

    -f becoming –ves


    Some nouns ending in –f are pluralized by dropping the –f and adding –ves:

    singular plural
    calf calves
    elf elves
    half halves
    hoof hooves
    knife knives
    leaf leaves
    life lives
    loaf loaves
    self selves
    shelf shelves
    thief thieves
    wife wives
    wolf wolves

    -is becoming –es

    Some nouns ending in –is are pluralized by dropping the –is and adding –es:

    singular plural
    axis axes
    analysis analyses
    basis bases
    crisis crises
    diagnosis diagnoses
    ellipsis ellipses
    emphasis emphases
    hypothesis hypotheses
    neurosis neuroses
    oasis oases
    paralysis paralyses
    parenthesis parentheses
    thesis theses

    -ix becoming –ices

    Some nouns ending in –ix are pluralized by dropping the –ix and adding –ices:

    singular plural
    appendix appendices
    index indices
    matrix matrices

    Unchanged plurals

    A few nouns are unchanged in their plural forms:

    singular plural
    barracks barracks
    deer deer
    fish fish
    gallows gallows
    means means
    offspring offspring
    series series
    sheep sheep
    species species


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    9. disqus_rZhQsk2w1O says

      I’ve graduated high school roughly 5 years ago and went to catholic school growing up, which was very strict about grammar/spelling. This page, and your site in general, is an amazing help to jog back memories about how certain endings change and which wording you’d correctly use to make a sentence proper. Thank you, this was very easy to comprehend! Keep up the great work, I’m glad to see the kids commenting here are actually gaining from this too! Truly wonderful.

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    13. Cog.xNight says

      How did I get here…?..

    14. Sorry, just one question. I don’t see person, child and some other irregular nouns. What happened to them? :D

    15. I.. always use the “sheeps” as a plural word.
      I have.. been enlightened.

    16. David Adrian Dieguez says

      Thanks for the post¡¡ I need a study english

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