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The Only Plural Nouns Guide You Need: Tips & Tricks to Master Every Form

In 1992, Dan Quayle was Vice President of the United States. During what should have been an uneventful appearance at an elementary school, something unexpected happened: he misspelled potato.

While younger generations won’t recall the event, this gaffe endured and the details are easy to find: Quayle’s Wikipedia page includes the subheading “Potatoe” within the chronology of his Vice Presidency, and Quayle himself penned an entire chapter on the subject for his memoirs.

You can trace the Vice President’s mistake (which he has attributed to cue cards provided by the school) back to a mixup between singular and plural nouns. His incorrect potatoe was halfway to the plural noun potatoes.

This guide to plural nouns is here to help you go beyond merely learning to define plural noun, providing guidance on their rules for formation and usage, as well.

Don’t forget: our plagiarism and spell check features can help you catch errors and typos and, with any luck, avoid large-scale public spelling embarrassments.

What is a Plural Noun?

The definition of plural noun can be summed up as a word used for more than one person, place, thing, or idea. Click to read more about increasing number for other parts of speech.

When a grammatical error occurs with this part of speech, the mistake is typically in the formation. Keep reading to learn the rules and see examples of regular and irregular structures.

Forming Regular Plural Nouns

Once you understand the plural noun definition, you’re ready to learn how to form regular and irregular plural nouns.

What is a regular plural noun example? Those considered regular follow standard rules (for the most part) to change their number.

Words Ending in Consonants

For words ending in most consonants, add an s:

  • dog = dogs
  • books = books

For those ending in s, sh, ch, z, or x, add es:

  • dish = dishes
  • box = boxes

Exception: if the ch sounds like a k, add only s: stomachs, lochs

Words Ending in Y

For words ending in y preceded by a consonant, change the y to i and add es:

  • country = countries
  • fly = flies

For words ending in y preceded by a vowel, add an s:

  • monkey = monkeys
  • toy = toys

Words Ending in F or Fe

For some words ending in f or fe, add an s:

  • roof = roofs
  • chef = chefs

Other words ending in f or fe change the f to v before adding s or es:

  • knife = knives
  • thief = thieves

Words Ending in O

For most words ending in o preceded by a vowel, add an s:

  • studio = studios
  • video = videos

Words ending in o preceded by a consonant usually change their number by adding es:

  • potato = potatoes
  • hero = heroes

Some words ending in o preceded by a consonant add only an s:

  • sopranos = sopranos
  • solo = solos

Finally, some words ending in o preceded by a consonant add either s or es, as both are considered correct:

  • mango = mangos/mangoes
  • banjo = banjos/banjoes

For guidance on which to use in your academic or professional writing, check with your style guide. Our citation resources can help guide you in APA format and more styles.

Forming Irregular Plural Nouns

A plural nouns’ definition changes only in number, but its spelling can change considerably if it is formed irregularly.

What is an irregular plural noun? Unlike their regular cousins, these words don’t follow any hard and fast rules in their formation. There are, however, some patterns that they follow, as seen in these examples of irregular plural nouns:

Irregular Formation Patterns

Words that swap oo for ee:

  • goose = geese
  • tooth = teeth

Words that swap a for e:

  • man = men
  • woman = women

Words that change considerably:

  • mouse = mice
  • person = people

Except: When referring to a computer mouse, use mouses, not mice.

Singular and Plural Nouns that Stay the Same

Some words do not change at all to increase their number. With this type of plural noun, the definition is determined through the context in which it is used.

  • fish
  • moose
  • buffalo

Fish, for example, refers to one fish in the phrase caught a fish. In the phrase plenty of fish, however, it refers to many fish.

For more examples of regular and irregular formation, see this.

Forming Plural Possessive Nouns

In this section, you’ll review examples of plural possessive nouns and learn how to form them.

The rules for forming plural possessive nouns can trip up even the most experienced writers. Luckily, they follow a short set of possible standards that can be quickly learned. If ever you’re unsure, consult with your style guide for confirmation or guidance. In addition to our citation creator, we also have style guide resources for MLA format, and others, that can help.

For a plural noun that ends in s, add an apostrophe to show possession:

  • the dogs’ bones
  • the knives’ blades
  • the designers’ clothes

For a plural noun that does not end in s, add ‘s to show possession:

  • men’s clothing
  • children’s room
  • people’s beliefs

Forming Compound Plural Nouns

Increasing the number of a compound word is another area that can seem tricky at first, but is easy to do once you learn the patterns that these words follow.

Compound words written as one word change their number by adding s or es:

  • spoonfuls
  • leftovers
  • letterheads

Compound words that are separated by spaces or joined by hyphens usually increase their number by adding an sto the primary word:

  • runners-up
  • poets laureate
  • lieutenant governors

The primary word is the word that is modified. If you’re unsure which word is being modified, you can figure it out by temporarily changing the number of all parts.

Mother-in-law, for example, is a compound to name one person. To identify the primary word, you need to identify which word is being modified. Using the tip above, you would figure this out by increasing the number for both parts and comparing their meanings.

What does each plural noun mean? Mothers refers to more than one mother, while laws is referring to more than one law. Mothers-in-law, therefore, is the correct formation, indicating more than one mother-in-law.

Some compound words increase their number irregularly:

  • drive-ins
  • six-year-olds
  • has-beens

Words that fall under the third rule are typically those with no apparent primary word. You’ll need to commit these outliers to memory, or else check a dictionary for help.

More Examples of Plural Nouns

Following the guidelines above will help you with the formation of most words. Some instances require additional consideration, such as when increasing the number for foreign words, numbers, letters, signs, and words considered as words.

Some foreign words increase number in their original language:

  • phenomenon = phenomena
  • analysis = analyses
  • alumnus = alumni/alumnae

English rules commonly change number for other foreign words:

  • formula = formulas
  • thesaurus = thesauruses
  • index = indexes

Some foreign words can use both the English and foreign formation, so check your dictionary or style guide to determine which form is appropriate when you’re unsure.

Finally, numbers, letters, signs, and words considered as words change their number by adding ‘s.

While these may seem out of place, remember: what is a plural noun? It’s a word identifying more than one person, place, thing, or idea. A plural noun is sometimes, then, formed from a word considered as a word, a number, a sign, or a letter. The examples below are in context for clarity:

Words considered as words:

  • She used three and’s in this sentence.


  • There are two 4’s and no 0’s in the answer.


  • To spell Mississippi, you’ll need four s’s and two p’s.


  • The company logo cleverly incorporates several +’s in its design.

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