Irregular Plurals can be found everywhere, like in the name of a famous kid’s book by Dr. Seuss One fish, two fish, red fish, blue fish. It’s one of the first books I read and the title contains an important tip regarding irregular plurals:

Be very careful when putting an S on the end of a noun!

Not all plurals end up having an S. Unfortunately.  However, we have some solutions for you, that should help. So let’s have a closer look.

We often hear phrases like “I caught two fishes yesterday,” or “I have two child”  in class, but as you have probably worked out, the correct version, following Dr Seuss’ lead, is “I caught two fish yesterday”. The video tip also names some other common irregular plurals:

Typical Irregular Plurals

Singular   Plural
sheep   sheep
person   people*
child   children
woman   women

*You can say one people and two peoples but the meaning is different from the regular way we talk about one person/two people. You use it when talking about the members of a particular nation, community, or ethnic group, e.g.

The native peoples of Australia (the different groups themselves; not the individuals).


Two of our favourite irregular plurals:

The last tip in the irregular plurals video addresses two very problematic words regarding the S at the end. In my experience, most people need to take the S from information and put it on headquarters ???? You may want to check this out. It’s a very common mistake you can easily avoid. 

information (never an S at the end)

headquarters (always an S at the end)

That means you say “It’s not much information” and “Our headquarters are in Munich”.


So, now you that know it’s not always as easy as popping an S on the end of the noun, we have put a list below to help you with finding more irregular plurals (This list is also found in our Much and Many blog). Take a close look at it, find the new ones important for you, and start memorising them. A simple tip is to write out the important ones on post-it notes, stick them somewhere you can see them very often, and within a week or two you’ll never forget them.


Irregular Plurals (a quick reminder that all the below plurals would be used with many)


Irregular plurals that change vowels

Singular              Plural

foot                     feet

tooth                  teeth

goose                  geese

man                    men

woman               women


Irregular plurals that change significantly

Singular              Plural

mouse                mice

die                       dice

ox                        oxen

child                    children

person                people


Irregular plurals that don’t change











Irregular plurals ending in -us

Singular              Plural

fungus                fungi

alumnus             alumni

radius                 radii

nucleus              nuclei

cactus                 cacti


Irregular plurals ending in -is

Singular              Plural

crisis                   crises

axis                     axes

analysis              analyses

thesis                  theses

Note that the pronunciation of the plural is CRY-sees


Irregular plurals ending in -on

Singular              Plural

phenomenon    phenomena

criterion             criteria


Irregular plurals ending in -um

Singular              Plural

bacterium          bacteria

datum                data

memorandum  memoranda

stratum              strata

curriculum         curricula

With these words, you have probably heard the plural more often than the singular.


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