Most singular nouns are made plural by simply putting an -s at the end. There are many different rules regarding pluralization depending on what letter a noun ends in. Irregular nouns do not follow plural noun rules, so they must be memorized or looked up in the dictionary.
Plural Noun Rules
There are many plural noun rules, and because we use nouns so frequently when writing, it’s important to know all of them! The correct spelling of plurals usually depends on what letter the singular noun ends in.
1 To make regular nouns plural, add ‑s to the end.
cat – cats
house – houses
2 If the singular noun ends in ‑s, -ss, -sh, -ch, -x, or -z, add ‑es to the end to make it plural.
truss – trusses
bus – buses
marsh – marshes
lunch – lunches
tax – taxes
blitz – blitzes
3 In some cases, singular nouns ending in -s or -z, require that you double the -s or -z prior to adding the -es for pluralization.
fez – fezzes
gas –gasses
4 If the noun ends with ‑f or ‑fe, the f is often changed to ‑ve before adding the -s to form the plural version.
wife – wives
wolf – wolves
Exceptions:
roof – roofs
belief – beliefs
chef – chefs
chief – chiefs
5 If a singular noun ends in ‑y and the letter before the -y is a consonant, change the ending to ‑ies to make the noun plural.
city – cities
puppy – puppies
6 If the singular noun ends in -y and the letter before the -y is a vowel, simply add an -s to make it plural.
ray – rays
boy – boys
7 If the singular noun ends in ‑o, add ‑es to make it plural.
potato – potatoes
tomato – tomatoes
Exceptions:
photo – photos
piano – pianos
halo – halos
With the unique word volcano, you can apply the standard pluralization for words that end in -o or not. It’s your choice! Both of the following are correct:
volcanoes
volcanos
8 If the singular noun ends in ‑us, the plural ending is frequently ‑i.
cactus – cacti
focus – foci
9 If the singular noun ends in ‑is, the plural ending is ‑es.
analysis – analyses
ellipsis – ellipses
10 If the singular noun ends in ‑on, the plural ending is ‑a.
phenomenon – phenomena
criterion – criteria
11 Some nouns don’t change at all when they’re pluralized.
sheep – sheep
series – series
species – species
deer –deer
You need to see these nouns in context to identify them as singular or plural. Consider the following sentence:
Mark caught one fish, but I caught three fish.
Plural Noun Rules for Irregular Nouns
Irregular nouns follow no specific rules, so it’s best to memorize these or look up the proper pluralization in the dictionary.
child – children
goose – geese
man – men
woman – women
tooth – teeth
foot – feet
mouse – mice
person – people
