Plural Spelling Rules

Singular and plural

A singular noun names one thing: cat, box, baby. A plural noun names more than one: cats, boxes, babies. Most plurals just add -s, but English has several spelling rules, and some words break every rule. This lesson collects them all in one place.

Rule 1: Add -s

Most nouns form the plural by adding -s.

book → books, tree → trees, girl → girls, pencil → pencils

Rule 2: Add -es after s, x, z, ch, sh

When a noun ends in s, x, z, ch or sh, add -es. Say the plural out loud: you can hear an extra syllable.

bus → buses, box → boxes, buzz → buzzes, lunch → lunches, dish → dishes, glass → glasses

Rule 3: Words ending in y

Look at the letter before the y.

• Consonant + y: change y to i and add -es: baby → babies, city → cities, story → stories, berry → berries
• Vowel + y: just add -s: boy → boys, key → keys, day → days, toy → toys

Names keep the y: the Kennedys.

Rule 4: Words ending in f or fe

Many change f or fe to v and add -es:

leaf → leaves, wolf → wolves, knife → knives, life → lives, half → halves, shelf → shelves

But some just add -s: roof → roofs, chef → chefs, cliff → cliffs, belief → beliefs. Check a dictionary when unsure.

Rule 5: Words ending in o

• Vowel + o: add -s: radio → radios, zoo → zoos, video → videos
• Consonant + o: many add -es: potato → potatoes, tomato → tomatoes, hero → heroes, echo → echoes
• But music and short words often add -s: piano → pianos, photo → photos, solo → solos

A memory trick: "The heroes ate potatoes and tomatoes."

Rule 6: Irregular plurals

An irregular plural follows no rule. These must be memorized.

Rule 7: Same in singular and plural

Some nouns do not change at all:

sheep, deer, fish, moose, bison, salmon, trout, aircraft, series, species

One deer, two deer. One moose, three moose.

Rule 8: Words from Latin and Greek

Some science and math words keep their original plurals:

cactus → cacti, fungus → fungi, nucleus → nuclei, crisis → crises, analysis → analyses, phenomenon → phenomena, criterion → criteria

Some now accept both: cactuses or cacti.

Compound nouns

Make the main word plural: mothers-in-law, passers-by, attorneys general. Closed compounds add -s at the end: toothbrushes, footballs.

Nouns that have no plural

A noncount noun cannot be counted, so it has no plural: water, milk, rice, sand, information, furniture, homework, advice, music. Instead, use a counting word: two glasses of water, three pieces of advice.

Worked examples

Example 1: fox → ends in x → foxes.

Example 2: pony → consonant + y → ponies.

Example 3: calf → f to v → calves.

Example 4: volcano → consonant + o, often -es → volcanoes (volcanos is also accepted).

Common mistakes

• Using an apostrophe for plurals: banana’s for sale ✗ → bananas ✓
• childs, mouses, sheeps ✗ → children, mice, sheep ✓
• monkies ✗ → monkeys ✓ (vowel + y)
• informations ✗ → information ✓

Try it yourself

1. Write plurals: church, lady, half, piano, goose.
2. Which are the same in singular and plural? moose, mouse, fish, fox.
3. Fix: The boy’s ate three peachs and two tomatos.
4. Write the plural of bus stop and sister-in-law.

Answers: 1. churches, ladies, halves, pianos, geese. 2. moose, fish. 3. The boys ate three peaches and two tomatoes. 4. bus stops, sisters-in-law.

Tip for families

Play "One and many." One person says a singular noun, and the other must say the plural and the rule it follows. Tricky words (octopus, person, roof) earn double points. Keep a list of the strangest plurals you find.

Quick recap

• Most plurals add -s; s, x, z, ch and sh add -es.
• Consonant + y becomes -ies; vowel + y just adds -s.
• Many f/fe words become -ves.
• Irregular plurals and unchanging nouns must be memorized.
• Never use an apostrophe to make a plural.