An all-inclusive guide to the rules of plural words


Just what is a plural noun?

The idea, in English, seems simple enough: take a singular noun and add an s, -es, sometimes -en, or similar suffix to give it a plural form. By and large, this approach works just fine.

But singular and plural, and what constitutes each, are not quite so simple all the time. There are nouns with multiple iterations, with spelling exceptions and modifications. And which form you use as a writer is almost wholly dependent on context.

From spelling irregularities to pilfering from other language traditions, let’s take a look at the ins and outs of plural nouns.

The basics

To start our study, here is a singular and plural words list:

Friend — friends

Neighbor — neighbors

Notebook — notebooks

Story — stories

Origin — origins

Hyperbole — hyperboles

Alliance — alliances (similarly: ally—allies)

Octopus — octopuses (yes, that’s really the correct plural!)

As you can see, there is a bit of slight modification from a spelling standpoint in (for example) words ending in y. Most of these words switch to an -ies ending when pluralized. This is distinct from words ending in -ey, which usually tack on an s (see our article on monkeys).

For the most part, this is the standard to adhere to when in doubt as to how to make a singular noun plural. Still, there is often plenty of room for doubt.

Linguistic exceptions

English is a conglomerate of Romance languages (descended from Latin) and Germanic and Anglo-Saxon languages. Many pluralization rules carry over from those linguistic traditions and appear in the English we speak today.


Here are some plural noun examples that would be categorized as exceptions to the traditional pluralization rule:

  • Child — children (from Anglo-Saxon)
  • Brother — brothers, or brethren (from Anglo-Saxon)
  • Here context is key — “brothers” typically refers to familial relations, whereas “brethren” is often used to signify a more spiritual or ideological bond
  • Index — indices (from Latin)
  • Similarly: codex — codices
  • Beau — beaus or beaux
  • This one is descended from French specifically; therefore, either the French (x) or English (s) rule of pluralization is acceptable. Typically the French looks more aesthetically pleasing.
  • Formula — formulas or formulae (from Latin)
  • Another holdover from Latin, this one accepts either plural, while words like antenna tend to take the Latin plural antennae, or minutia — minutiae.
  • Criterion — criteria (from Greek)

Sometimes the word criteria is treated like a singular noun, but in reality it is a pluralization of criterion.

In a related vein, you have some words which were imported directly from these other languages and abide by their own pluralization rules. For example:

  •  Alumnus — alumni (male, Latin)
  •  Alumna — alumnae (female, Latin)
  •  Addendum — addenda (neuter, Latin)

Two in one

Sometimes a word’s plural form requires no discernible change from its singular form — no discernible change in the word itself, at least.

Here are some examples of nouns that are both singular and plural:

  • species
  • family
  • money
  • people
  • fish

These can be at once easier and trickier to use in a sentence because their form does not change. The singular form of species is the same as the plural form: what signifies which form it takes is the verb conjugation in the surrounding sentence. As a reader, you have to use context clues; as a writer, you have to provide them.

The context for the above examples:

  • Species (singular): Thus far science has found Homo sapiens to be the only species with advanced cognitive functions.
  • Species (plural): You will find many species cohabitating peacefully in the ocean.
  • Family: As we’ve covered before, American English tends to classify this word as a singular noun, British English as a plural one. But you could say “My family is visiting this weekend” or “My family are visiting this weekend” and you would be understood.
  • Money: This is what we will call a collective noun, in that it refers to a group of something (units of currency) but is usually treated as a single entity. You have “more money” or “less money,” but you would refer to it in total as “all your money.”
  • People: This one differs based on the authorial tone you are trying to strike. “People,” in general, constitute a plural noun; but “a people” is a national or political unit, distinguished from other peoples by ethnicity or background.
  • Fish: It is most commonly accepted to say “a fish” to refer to a single fish and “fish” to refer to a group of them. However, “fishes” is also an acceptable plural—less common, but not technically incorrect.

Then you’ve got a word like cannoli, which is in its Italian plural form already but has been bastardized to accommodate the English pluralization cannolis. As we have said, it all depends on context; in this case, it also depends on the level of authenticity you are going for.

The occasional false plural

Every once in a while you will come across a word which looks like a plural, or like it should be a plural, but is not. A great example of this is the word politics—it’s actually a singlular noun, despite ending in the signature s.


His politics is very different from mine, but we still get along.

Politics is usually a sensitive subject.

That said, when referred to in a collective context, a pluralization will sound acceptable and natural.


Our politics are not aligned, so we tend to steer clear of the subject.

Nouns with no singular

Some plural nouns are rarely, if ever, used in singular form; you only ever hear them used to refer to a collective. Most of these, to hearken back to our segment on linguistic lineages, have roots in Latin. For example:

  • ephemera
  • memorabilia
  • stigmata (usually discussed in religious contexts)

The exceptions to the rules of English pluralization nearly equal the number of rules themselves, and it can be hard to know where to begin if you have not studied them from a young age. We hope this guide has supplied you with an adequate foundation. There will always be more to discover—all you can do is find someplace (or places) to start!

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