Plural Nouns

English Grammar Rules

In general the plural of a noun is formed by adding -S to the noun.

Singular	Plural
car	cars
house	houses
book	books
bird	birds
pencil	pencils

However:
1. When the noun ends in SS, SH, CH or X, we add -ES to the noun.

Singular	Plural
kiss	kisses
wish	wishes
match	matches
box	boxes
fox	foxes

• I have a box in my bedroom.
  
• I have three boxes in my bedroom.

2. When the noun ends in a VOWEL + Y, we add -S to the noun.

Singular	Plural
boy	boys
holiday	holidays
key	keys
guy	guys

3. When the noun ends in a CONSONANT + Y, we remove Y and add -IES to the noun.

Singular	Plural
party	parties
lady	ladies
story	stories
nanny	nannies
city	cities

4. If the noun ends in F or FE, we remove the F/FE and add -VES to the noun.

Singular	Plural
life	lives
leaf	leaves
thief	thieves
wife	wives

5. If the noun ends in IS, we change it to ES.

Singular	Plural
analysis	analyses
basis	bases
crisis	crises

6. There are a number of nouns that don't follow these rules. They are irregular and you need to learn them individually because they don't normally have an S on the end.

Singular	Plural
man	men
woman	women
child	children
foot	feet
tooth	teeth
goose	geese
mouse	mice

• There is a child in the park.
  
• There are many children in the park.

7. There are some nouns in English that are the same in the singular and the plural.

Singular	Plural
fish	fish
sheep	sheep
deer	deer
moose	moose
aircraft	aircraft

• I can see a sheep in the field.
  
• I can see ten sheep in the field.

Sometimes you will hear the word fishes (especially in songs) though it is grammatically incorrect.

Reference : http://www.grammar.cl/Notes/Plural_Nouns.htm