Hi guys!

Have you ever wondered, for example, why the plural of wolf is wolves, and not wolfs? Well, in English there are many nouns that don’t follow the standard rules for pluralization. In this free English lesson, I will go through some of them and show you how irregular nouns form their plural forms.

irregular nouns, plural, noun, english grammar

As you know, most countable nouns have a regular plural in  -s/-es. Irregular nouns form plurals in a number of different ways, for example, by changing a vowel or consonant sound or by adding an unusual ending.

Let’s focus first on vowel changes.

Vowel changes

  • Some plurals are formed by changing the vowel sound.

So, for example you have:


foot- feet

goose- geese

man- men

mouse- mice

tooth- teeth

woman- women

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There are also irregular noun plurals in which there are changes of consonants.

  • With some nouns we change f to v, and then we add -s/-es.

calf – calves

life – lives

wife – wives

half – halves

loaf – loaves

wolf – wolves

knife – knives

shelf – shelves

leaf – leaves

thief – thieves

  • Some nouns ending in f or fe are regular, such as beliefs, chiefs, cliffs, safes.

  • There are also two nouns which form plural by adding -en.

child – children

ox – oxen

  • When we are talking about an amount of money, we use pence as the plural of penny.

Fifty-five pence, please.

    • Pennies are individual penny coins.

  • Person has two plurals: persons and people.

Authorized persons only may enter.

There were lots of people at the concert.

  • A people is a large group such as a nation.

The Scots are a fair-skinned people.


  • There are also some nouns which do not change in the plural.

    • Such nouns are aircraft, hovercraft, spacecraft; some nouns for animals – sheep, deer; and some kinds of fish – cod, salmon.


Foreign nouns

There are also a number of foreign words which have come into English from other languages, such as Latin and Greek, and these nouns have plural endings which are not so common in English. The only way you can learn them is to try to memorize them.

  • Foreign nouns ending in -on or -um form plural by changing -on/-um to -a.

criterion – criteria

curriculum – curricula

medium – media

phenomenon – phenomena

English Grammar Lesson- Irregular Noun plurals
  • Foreign nouns ending in -a form plural by changing -a to -ae.

formula – formulas / formulae

alga – algae

  • Foreign nouns ending in -is form plural by changing -is to -es.

analysis – analyses

crisis – crises

hypothesis – hypotheses

  • Foreign nouns ending in -us form plural by changing -us to -i.

cactus – cacti / cactuses

nucleus – nuclei

stimulus – stimuli

  • But, remember, not every noun ending in on, um, or us has an irregular ending.

electron – electrons

museum – museums

bonus – bonuses


I listed some foreign nouns and their plural forms to help you learn them. Go through these and try to memorize them


agenda – agendas

alga – algae

alumnus – alumni

alumna – alumnae

analysis – analyses

apex – apexes

aquarium – aquariums

atrium – atria

avocado – avocados

axis – axes

bacterium – bacteria

bistro – bistros

basis – bases

casino – casinos

criterion – criteria

diagnosis – diagnoses

domino – dominoes

echo – echoes

ego – egos

ellipsis – ellipses

embargo – embargoes

kangaroo – kangaroos

larva – larvae

oasis – oases

paparazzo – paparazzi

paralysis – paralyses

pistachio – pistachios

phenomenon – phenomena

portfolio – portfolios

potato – potatoes

radio – radios

stimulus – stimuli

studio – studios

synopsis – synopses

thesis – theses

veto – vetoes

zoo – zoos

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