Singular and Plural Nouns in English

1. Basic Rule: Add –s

cat → cats
book → books
car → cars
plate → plates

dog → dogs
apple → apples
banana → bananas
orange → oranges
bird → birds
birthday → birthdays
present → presents
animal → animals
monkey → monkeys
pencil → pencils

2. Add –es for Nouns Ending in s, x, z, ch, sh

Use –es for words ending in s, x, z, ch, sh

bus → buses
box → boxes
quiz → quizzes (requires doubling the "z")
church → churches
dish → dishes

fox → foxes
match → matches
lunch → lunches
peach → peaches
watch → watches
wish → wishes
brush → brushes

3. Nouns Ending in -o

Add –es for Nouns Ending in Consonant + o

tomato → tomatoes
potato → potatoes
hero → heroes
echo → echoes
torpedo → torpedoes
tornado → tornadoes
domino → dominoes

mango → mangoes / mangos *
cargo → cargoes / cargos *
mosquito → mosquitoes / mosquitos *
volcano → volcanoes / volcanos *
buffalo → buffaloes / buffalos *

* Adding -es is more common. But adding –s is considered acceptable too.

Add –s for Nouns Ending in Vowel + o

zoo → zoos
radio → radios
studio → studios
video → videos
kangaroo → kangaroos
portfolio → portfolios
bamboo → bamboos

Exception.:

piano → pianos
photo → photos
memo → memos
casino → casinos
piccolo → piccolos
zero * → zeros / zeroes
* Both "zeros" and "zeros" are correct. But "zeros" is more common and widely accepted.
avocado → avocados / avocadoes *

* Both "avocados" and "avocadoes" are correct plural forms of the word "avocado". While "avocados" is more common and widely accepted, "avocadoes" is also grammatically correct, following the general rule of adding "-es" to nouns ending in a consonant + "o".

4. Nouns Ending in –y

If a noun ends in a consonant + y, change y to ies:

baby → babies
city → cities
story → stories
country → countries

spy → spies
army → armies
puppy → puppies
butterfly → butterflies
cherry → cherries

But if the noun ends in a vowel + y, just add –s:

toy → toys
key → keys
boy → boys
day → days
guy → guys

5. Change –f or –fe to –ves

For some nouns ending in –f or –fe, you switch to –ves:

knife → knives
leaf → leaves
wolf → wolves
life → lives
thief → thieves
shelf → shelves
scarf → scarves

loaf → loaves
wife → wives
calf → calves
elf → elves
half → halves
self → selves

⚠️ Not all of them change—some just get –s

roof → roofs
belief → beliefs
chef → chefs
cliff → cliffs
chief → chiefs

6. Irregular Plurals: No Clear Pattern

man → men
woman → women
child → children
person → people
foot → feet
tooth → teeth
mouse → mice

goose → geese
ox → oxen
crisis → crises
criterion → criteria
phenomenon → phenomena
stimulus → stimuli
cactus → cacti
focus → foci
nucleus → nuclei
fungus → fungi
louse → lice
thesis → theses
datum → data
appendix → appendices
syllabus → syllabi

7. Unchanging Plural Nouns

Some nouns stay the same. They also called Invariable Nouns

aircraft → aircraft

So whether you're talking about one jet or an entire fleet, you just say aircraft. No "s", no "es".

Other nouns like this include:

aircraft → aircraft
sheep → sheep
deer → deer
salmon → salmon
tuna → tuna
fish → fish

The word "fish" is both the singular and plural form:

"I caught one fish."

"We saw ten fish in the pond."

But, you can say fishes when you're talking about multiple species of fish:

"The aquarium contains fishes from the Amazon, the Pacific, and the Atlantic."

species → species
series → series
trout → trout
moose → moose
bison → bison
swine → swine
cod → cod
reindeer → reindeer
offspring → offspring
headquarters → headquarters

8. Plural-Only Noun

Some nouns are already plural by nature.

They all refer to things that are essentially one item, but made of two parts—so the plural form is the default.

trousers
jeans
shorts
scissors
glasses