How to Form Plural Nouns? Rules and Examples

Most English nouns form their plurals by adding “-s,” but there are many exceptions. Some require “-es,” others change their spelling, and a few remain the same in singular and plural forms. Understanding these patterns and exceptions ensures you can correctly form plural nouns.

Table of contents

What Are Plural Nouns?

Plural nouns refer to more than one person, place, thing, or idea. For example:

• Singular: cat → Plural: cats
• Singular: house → Plural: houses

Most regular nouns follow simple rules to become plural.

The Basic Rule: Add “-s”

For most regular nouns, simply add “-s” to form the plural:

Examples:

• cat → cats
• house → houses
• book → books
• car → cars

When to Add “-es”

Use “-es” for nouns ending in certain letters or sounds, typically when the singular form ends in a sibilant or hissing sound. These endings include “-s,” “-ss,” “-sh,” “-ch” (with a certain sound), “-x,” and “-z.”

Examples:

• bus → buses
• kiss → kisses
• brush → brushes
• watch → watches
• box → boxes
• quiz → quizzes

Note on “-ch” Endings

Most nouns ending in “-ch” take “-es” because “-ch” often represents a “tch” sound (e.g., watch → watches, church → churches). However, if the “ch” at the end sounds like a “k” (a hard, non-sibilant sound), then the plural is formed by adding only “-s.”

Examples:

• stomach → stomachs (not stomaches)
• monarch → monarchs (not monarches)
• epoch → epochs
• tech (short for technology in some contexts) → techs

In these words, the final “ch” sounds more like a “k,” so add just “-s.”

Nouns Ending in “-y”

If a noun ends in a consonant + y, change “y” to “i” and add “-es.”

Examples:

• baby → babies
• city → cities
• lady → ladies
• penny → pennies

If a noun ends in a vowel + y, simply add “-s.”

Examples:

• day → days
• key → keys
• boy → boys

Nouns Ending in “-f” or “-fe”

For many nouns ending in “-f” or “-fe,” change the “f” to “v” and add “-es.”

Examples:

• leaf → leaves
• wolf → wolves
• knife → knives
• wife → wives

Exceptions:

• roof → roofs
• belief → beliefs
• chief → chiefs

Nouns ending in -o (sometimes -s, sometimes -es):

Add “-es” if the word ends in a consonant + o

• Potato → Potatoes
• Hero → Heroes
• Echo → Echoes

Just “-s” if the word ends in a vowel + o

• Radio → Radios
• Video → Videos
• Kangaroo → Kangaroos

Here’s a table summarizing all the rules for forming regular plural nouns in English:

These rules cover most cases of regular plural noun formation.

Irregular Plurals

Some nouns have irregular forms that do not follow the standard rules:

1. Change the vowel:
   • man → men
   • woman → women
   • foot → feet
   • tooth → teeth
   • goose → geese
   • mouse → mice
   • louse → lice
2. Entirely different word:
   • child → children
   • person → people
   • ox → oxen
3. No change:
   • sheep → sheep
   • deer → deer
   • fish → fish
   • species → species
   • series → series

For these irregular forms, memorization is the key.

Foreign Words

Some borrowed words keep their original plural form:

• medium → media
• datum → data
• curriculum → curricula
• memorandum → memoranda
• cactus → cacti (also cactuses)
• focus → foci (also focuses)
• index → indices (also indexes)
• phenomenon → phenomena
• criterion → criteria

Modern English often allows Anglicized plurals (e.g., “curriculums,” “indexes”) depending on context and formality.

Compound Nouns

For compound nouns, typically pluralize the main word:

• mother-in-law → mothers-in-law
• attorney-at-law → attorneys-at-law
• passer-by → passers-by

Abbreviations, Acronyms, and Letters

• For abbreviations, acronyms, and acronyms used as words: just add “-s” (no apostrophe needed).
  • DVD → DVDs
  • ATM → ATMs
  • PhD → PhDs
• For letters, numbers, and symbols, add “-s” (or “-’s” for clarity) depending on style guides:
  • Mind your p’s and q’s.
  • Writing lots of 7s.
  • Several &s in the text.

Seasons and Directions

• Seasons (spring, summer, autumn/fall, winter) are not usually pluralized as they refer to a category rather than countable items.
• Directions (north, south, east, west) typically form regular plurals if treated as countable nouns in certain contexts:
  • “The winds came from the norths” (very rare usage) Generally, directions are not pluralized because they are abstract concepts.

Style and Reference

• Check dictionaries for words ending in “-o,” “-ch,” or rare words that may have unusual plural forms.
• Some style guides specify preferences for plural forms of certain nouns, especially for foreign words.

Summary of Rules

1. Add “-s” for most words:
   book → books
2. Add “-es” to nouns ending in s, ss, sh, ch (tch sound), x, z:
   match → matches, bus → buses
3. For nouns ending in ch sounding like “k,” add only “-s”:
   stomach → stomachs, monarch → monarchs
4. For nouns ending in consonant + y: change y to i and add -es:
   baby → babies
5. For nouns ending in vowel + y: add -s:
   boy → boys
6. For nouns ending in f or fe: often change to v and add -es:
   leaf → leaves
7. Irregular plurals: must be memorized:
   man → men, child → children
8. Foreign words: may keep original plural or accept English forms:
   datum → data
9. Compound nouns: pluralize the main word:
   mother-in-law → mothers-in-law
10. Acronyms, abbreviations: usually just add -s:
    DVD → DVDs

Practice Exercises

1. Choose the correct plural form:
   • calf: calves or calfs?
   • zero: zeros or zeroes?
   • avocado: avocados or avocadoes?
   • hero: heros or heroes?
   • monarch: monarches or monarchs?
2. Correct the following:
   • “We saw many foxs in the field.”
   • “He has three criterias.”
   • “They bought two pianoes.”
3. Provide the plural:
   • echo
   • goose
   • phenomenon
   • woman
   • loaf

Suggested Answers

1. Correct plurals:
   • calf → calves
   • zero → zeros (or zeroes is also acceptable, but zeros is more common)
   • avocado → avocados (usually just add s)
   • hero → heroes (o ending, add es)
   • monarch → monarchs (ch sounding like k, add s)
2. Corrections:
   • “We saw many foxes in the field.”
   • “He has three criteria.” (criterion → criteria)
   • “They bought two pianos.” (words ending in o can vary, but piano → pianos is standard)
3. Provide the plural:
   • echo → echoes
   • goose → geese
   • phenomenon → phenomena
   • woman → women
   • loaf → loaves

Forming plurals in English often involves adding “-s” or “-es,” but a variety of special rules and exceptions exist. Knowing which rule applies—especially for words ending in “-o” or “-ch” (with different sounds), nouns ending in “-y,” and irregular nouns—is essential for correct spelling. Regular practice, consulting dictionaries, and exposure to well-written English will reinforce these rules and help you learn pluralization.