Different languages have different ways of expressing the difference between singular and plural nouns. Understanding the difference between plural and singular nouns is an important part of learning and using the English language. If used incorrectly, you can easily miscommunicate even the most obvious of details. The difference between the two types is equally important whether the language is being spoken or written.
Primary Difference
The primary difference between plural and singular nouns is that the latter indicates a single unit of the noun while the former represents multiple units. It's important to make the distinction between the two tenses because shared characteristics in nouns will otherwise go unnoticed. The plural form of nouns can commonly be confused with the possessive version of a noun, which indicates ownership. Possessive nouns often contain an apostrophe while plural nouns do not.
Creating Plural Form
The majority of nouns in the English language can be transformed from singular to plural simply by adding an "s" to the word's end; for example, there is one car, but if another arrives, there are two cars. Words that end in the letters "s", "-ch", "x", or "s"-like sounds become plural by adding "es" to the end. For example, oxygen is not one gas, but a combination of gases. Not all words adhere to these principles, though, as some nouns take on different forms when they become plural.
Latin and Greek Plural Forms
Nouns that are not made plural by simply adding "s" or "es" sometimes take on unique forms rooted in their original Latin or Greek forms. For example, the word criterion is used to describe a standard upon which a judgment is made. If there are more than one of these standards, then there would be "criteria" instead of a list of "criterions," which would be the incorrect form.
Alternative Noun Endings
Nouns which end in the letters "o" and "y" can also take unique form when transforming from singular to plural. Singular nouns that end in "o" are often turned plural by adding an "es" to the end. Nouns that end in "y" are often turned plural by removing the "y" and adding "ies" to the end. For example, the word "supply" in the singular form is transformed to "supplies" when turned plural.