50+ Irregular Plural Nouns in English

Let’s learn 50 irregular plural nouns – these are nouns that don’t follow the normal rules for forming plurals! Even a lot of native English speakers aren’t sure about how to make the plural forms of these words. When you learn them, you can avoid mistakes and then be confident that your English is correct.

Let’s quickly review how we form regular plural nouns, and then we’ll get to the irregular ones and more complicated cases.

Regular Plural Nouns:

Add -S

Nouns Ending In -Ch, -Sh, -X, -S Sounds:

Add -ES

Exceptions: stomach/stomachs, matrix / matrices

Nouns Ending In consonant-Y:

End With -IES

If the noun ends in vowel-y: just add -S

• day – days
• key – keys
• toy – toys

Nouns Ending In -O:

-S Or -ES (Depends On The Word!)

Words that end in a vowel + o: Just add -s

Musical words: Just add -s

Words from Italian/Spanish: Just add -s

• taco – tacos
• avocado – avocados
• tornado – tornados
• casino – casinos

Shortened words: Just add -s

Always –ES:

• potato/tomato – potatoes/tomatoes
• hero – heroes
• torpedo – torpedoes
• echo – echoes

Some can be both!

• ghetto – ghettos / ghettoes
• mango – mangos / mangoes
• mosquito – mosquitos / mosquitoes
• volcano – volcanos / volcanoes

Nouns Ending In -F Sound: Change To -VES

Exceptions: chef/chefs and roof/roofs

VERY Irregular Nouns

• man – men
• woman – women
• child – children
• person – people
• tooth – teeth
• foot – feet
• die – dice
• vertebra – vertebrae
• antenna – antennas (electrical) and antennae (insects)
• mouse – mice
• goose – geese
• ox – oxen

Nouns with the same singular and plural form

• one sheep, two sheep
• one deer, two deer
• one fish, two fish
• one series, two series
• one species, two species

Latin/Greek Nouns: US –> I

• alumnus/alumna – alumni
• cactus – cacti
• focus – foci
  Some people do say “focuses.” Alternatively, you could say “points of focus” or “focal points” for the plural of “focus”
• fungus – fungi
• nucleus – nuclei
• stimulus – stimuli
• syllabus – syllabi

Latin/Greek Nouns: IS –> ES

Latin/Greek Nouns: UM/ON –> A

Do you think you can remember all those irregular plural nouns? Try using as many as you can in sentences!

And I’d like to invite you to join me inside my Advanced English Grammar Course. If you’re really looking to take your English to the next level in just about 15 minutes a day, this course will help you get there.