Introduction to Irregular Nouns
In English, we usually form the plural of nouns by adding -s or -es. These are called regular nouns. However, some nouns do not follow this rule and form their plural in an irregular way. These are called irregular nouns.
While some irregular nouns need to be memorized, there are patterns that can help you remember them. Below, we have categorized different types of irregular plurals to make learning them easier.
Irregular Nouns: Quick Guide
| Singular Form | Plural Form | |
|---|---|---|
| nouns ending in-fe | → | changes to -ves |
| nouns ending in-f | → | changes to-ves |
| nouns ending in-o | → | add -es |
| nouns ending in -us | → | changes to -i |
| nouns ending in -is | → | changes to -es |
| nouns ending in -on | → | changes to -a |
| nouns ending in -um | → | changes to -ia |
| nouns ending in -ix | → | changes to -ices, -xes |
| nouns ending in -a | → | changes to -ae |
| nouns ending in -z or -s | → | double the consonant and add |
| no change (singular = plural) | → | remains the same in both forms |
| other changes | → | vowel changes |
| → | complete word changes |
Irregular Nouns: Same Singular and Plural Forms
Some irregular nouns have the same form in both singular and plural. These nouns are countable, so they should not be confused with uncountable nouns.
| Singular Form | Plural Form |
| aircraft | aircraft |
| barracks | barracks |
| bison | bison |
| buffalo | buffalo, buffaloes |
| crossroads | crossroads |
| deer | deer |
| dozen | dozen |
| elk | elk |
| fish | fish |
| grouse | grouse |
| headquarters | headquarters |
| horsepower | horsepower |
| hundred | hundred |
| million | million |
| moose | moose |
| offspring | offspring |
| salmon | salmon, salmons |
| series | series |
| sheep | sheep |
| shrimp | shrimp, shrimps |
| swine | swine |
| trout | trout |
Irregular Nouns: Ending in -f or -fe → -ves
| Singular Form | Plural Form |
| calf | calves |
| elf | elves |
| half | halves |
| knife | knives |
| leaf | leaves |
| life | lives |
| loaf | loaves |
| sheaf | sheaves |
| shelf | shelves |
| thief | thieves |
| wife | wives |
| wolf | wolves |
Exceptions:
Irregular Nouns with Two Plural Forms
Some nouns have two acceptable plural forms.
Irregular Nouns: Ending in -o (-oes)
| Singular Form | Plural Form |
| domino | dominoes |
| echo | echoes |
| hero | heroes |
| mango | mangoes, mangos |
| motto | mottoes, mottos |
| potato | potatoes |
| tomato | tomatoes |
| tornado | tornadoes, tornados |
| volcano | volcanoes, volcanos |
Exceptions
Words from other languages ending in -o:
Irregular Nouns: Latin and Greek Origins
Some English nouns have irregular Latin or Greek plurals.
ending in -us
| Singular Form | Plural Form |
| cactus | cacti |
| focus | foci, focuses |
| fungus | fungi |
| nucleus | nuclei, nucleuses |
| octopus | octopi, octopuses |
| syllabus | syllabi |
| radius | radii, radiuses |
Exceptions:
-is → -es
| Singular Form | Plural Form |
| analysis | analyses |
| axis | axes |
| crisis | crises |
| oasis | oases |
| prognosis | prognoses |
| thesis | theses |
-on → -a
| Singular Form | Plural Form |
| criterion | criteria |
| phenomenon | phenomena |
-um → -a
| Singular Form | Plural Form |
| bacterium | bacteria |
| curriculum | curricula |
| datum | data |
| erratum | errata |
| medium | media |
| memorandum | memoranda |
| stratum | strata |
-x → -ices, -xes
| Singular Form | Plural Form |
| appendix | appendices, appendixes |
| index | indices, indexes |
| vortex | vortices, vortexes |
-a → -ae
| Singular Form | Plural Form |
| alumna | alumnae |
| antenna | antennae, antennas |
| larva | larvae, larvas |
| nebula | nebulae, nebulas |
Irregular Nouns: Vowel Changes
Some irregular nouns change their internal vowels.
| Singular Form | Plural Form |
| foot | feet |
| goose | geese |
| man | men |
| tooth | teeth |
Irregular Nouns: Doubling Consonants -s or -z
Some nouns ending in -s or -z double the consonant before adding -es.
| Singular Form | Plural Form |
| bus | busses (AmE) |
| gas | gasses |
| quiz | quizzes |
Irregular Nouns: Complete Word Changes
| Singular Form | Plural Form |
| child | children |
| die | dice |
| louse | lice |
| mouse | mice |
| ox | oxen |
| person | people |
Regular Nouns: How to Form the Plural
Forming the plural in English is quite easy. We add the ending -s or -es, and with words ending in vowel+y we change the y to i.
NOUN + S
| Singular Form | Plural Form |
| animal | animals |
| bag | bags |
| book | books |
| closet | closets |
| computer | computers |
| dog | dogs |
| shoe | shoes |
| table | tables |
NOUNS ENDING IN -S, -SS, -SH, -CH, -X, -Z + ES
| Singular Form | Plural Form |
| arch | arches |
| atlas | atlases |
| beach | beaches |
| bus | buses (BrE) |
| bush | bushes |
| boss | bosses |
| box | boxes |
| branch | branches |
| brush | brushes |
| church | churches |
| dish | dishes |
| kiss | kisses |
| match | matches |
| pass | passes |
| scratch | scratches |
| tax | taxes |
CONSONANT + Y ⇒ -IES
Words ending in -y change to -ies.
| Singular Form | Plural Form |
| baby | babies |
| berry | berries |
| body | bodies |
| cherry | cherries |
| city | cities |
| copy | copies |
| country | countries |
| dictionary | dictionaries |
| enemy | enemies |
| family | families |
| fly | flies |
| gallery | galleries |
| lady | ladies |
| nanny | nannies |
| poppy | poppies |
| puppy | puppies |
| spy | spies |
| story | stories |
VOWEL + Y ⇒ -YS
| Singular Form | Plural Form |
| boy | boys |
| day | days |
| donkey | donkeys |
| key | keys |
| kidney | kidneys |
| monkey | monkeys |
| toy | toys |
| tray | trays |
Uncountable Nouns
Some nouns cannot be counted and do not have a plural form.
To learn more, see Countable and Uncountable Nouns.
