Summary
In-depth Explanation
Since the form of these nouns doesn’t change, you must use context to determine whether the noun is singular or plural (often the verb form used with the noun). For example:
The sheep is grazing in the field.
The sheep are grazing in the field.
You can tell that “sheep” in the first sentence refers to just one because the singular verb form “is” is used. In the second sentence, the verb “are” shows that “sheep” refers to more than one.
Examples of Singular/Plural Nouns
Here are some more nouns related to living things that are the same in the singular and plural:
fish*
moose
bison
deer
species
offspring
*Note: “Fishes” is used in scientific contexts to refer to different species of fish. Here’s an example in context:
Singular: I saw a deer in the forest.
Plural: We saw three deer near the river.
There are also some invariant nouns related to objects or technology. For example:
aircraft
headquarters
crossroads
series
Here’s an example in context:
Singular: The series was a hit on TV.
Plural: Several new series are being released this year.
How to Use Invariable Nouns
Even though the noun looks the same, the verb must agree with whether the noun is singular or plural. For example:
The fish swims quickly. (refers to one fish)
The fish swim quickly. (refers to multiple fish)
Remember not to add an “-s” to these nouns to make them plural. For example:
Incorrect: She saw three sheeps in the pen.
Correct: She saw three sheep in the pen.
Plural Invariant Nouns
There are also some nouns that are referred to as plural invariant nouns. They don’t have a singular form and are only used in the plural. For example:
scissors
pants
jeans
shorts
However, we can use these nouns to refer to a singular or plural object. For example:
I bought a new pair of pants. (singular)
All of my pants are in the laundry. (plural)
My pants are too tight. (could be singular or plural, depending on context)