Perplexing Plurals: Nouns That Don’t Follow the Rules

Tuesday, January 31 3 min read

The simplest plural rule in English is to add an “s” to the end of a noun to make it plural (or “es” if the noun ends in “s” or “x”). For example, “one cat” becomes “two cats,” “one box” becomes “two boxes,” and “one cactus” becomes “two cactuses.” But wait — that last one doesn’t sound right. Here’s where the rules for plurals become tricky. Because English words are often borrowed from other languages, not all terms can become plural by adding “s” or “es” to the end. Moreover, not all words even have a distinct plural form.

Irregular Greek & Latin Plurals

Many English words come from Greek and Latin, and that’s why they don’t follow the standard English “-s/-es” rules for plurals. Instead, they use the grammar rules from their root languages.

For nouns ending in “a,” adding “e” to the end of the word makes it plural:

antenna → antennae

larva → larvae

nebula → nebulae

When the word ends in “um,” that syllable is replaced by an “a”:

curriculum → curricula
medium → media
symposium → symposia

If the noun ends in “us,” make it plural by swapping “i” for “us”:

cactus cacti

fungus → fungi

stimulus → stimuli

The word “octopus” is a grammar trickster. Several plural forms are commonly used — “octopuses,” “octopi,” “octopodes,” and “octopods” — but only a few are correct. The first, with the simple “-es” ending, is the standard English plural. However, “octopus” comes from Greek, so following the Greek plural form and using “octopodes” would also be correct. “Octopi” is the Latin formation, so it is incorrect. “Octopods” sounds like a useful comic-book creation, but it’s not accurate according to any grammar rules.

Mass Nouns

While some nouns are challenging to change into plurals, others don’t change at all. The vast majority of nouns are “count nouns,” meaning they describe a person, place, or thing that can be counted. Think of it this way: If you can put a number in front of the noun, it’s a count noun. Pluralizing these words is simple.

One bus → Two buses

One dog → Three dogs

One hat → Five hats

However, there are some nouns you can’t count, and these are called “mass nouns.” For example, the word “greed” is a mass noun, because the exact quantity of greed someone has can’t be counted. A person can’t have one greed or two greeds; therefore, “greed” is an uncountable or mass noun.

Mass nouns only have a singular form and should not be used with plural verbs:

The weather is nice outside today. NOT The weather are nice outside today.

Money is the root of all evil. NOT Money are the root of all evil.

Even if a mass noun ends in “s,” it should still be considered singular. Examples include “electronics” and “measles.”

Instead of using an indefinite article (“a” or “an”) before a mass noun, use a descriptive word to explain the quantity.

A bag of sugar

A tube of toothpaste

A lump of coal

Select words can be both mass and count nouns. “Hair” describes all the strands growing from a person’s head. (“She dyed her hair blonde.”) But every individual hair can also be counted. (“She found two gray hairs.”)

More Irregular Plurals

Finally, some plurals refuse to play by the rules. These words don’t change between their singular and plural forms but should always be used with the appropriate singular or plural verb.

One moose is crossing the road. → Three moose are crossing the road.

One sheep is grazing in the field. → Four sheep are grazing in the field.

One shrimp is swimming in the tank. → Ten shrimp are swimming in the tank.

Sometimes these are called “invariants” because they don’t change from their singular to plural forms. Many animal nouns — “bison,” “deer,” “salmon,” and “squid,” for example — fall in this category.

Featured image credit: malerapaso / iStock

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