In grammar, nouns are defined as words that stand for persons, places, or things. A word that takes the place of a person is a noun. A word that stands for a place is a noun. A word that can be used to bring up a mental picture of a thing like a river is a noun. However, there are sub-divisions in nouns. Now, let us talk about Count and non count nouns.
There can be more than one river. To represent the idea of more than one river or of a generic river or rivers in general, we can add an “s” to the ending of river and get rivers. A river would be used to denote a river like the Ohio River. By adding an “s” we have made a generic concept and the noun “rivers” is now used or can be used to represent all of the rivers in the world with no particular river in mind. “River” can also be grammatically called a noun that can be counted or a count noun. For the most part, nouns are words that were invented to denote persons, places or things. There are words sometimes used as adjectives that can also be used as nouns. That is what we are talking about when we refer to Count and non count nouns.
There are other words that can be used as nouns when we are talking about the parts of a sentence. We normally think of a subject as being a noun. But, there are some words that can be used as subjects and are therefore used as a noun in a sentence that represents state of being. If the sentence read, “The jealousy in her mind raged.” The word “jealousy” is used as a noun. However, it can’t be made into a word encompassing all of the feelings encompassed by the word “jealousy” since jealousy is a personal state of being or an emotion that is not concrete. No one can see a “jealousy”. One can have a mental image of what one perceives “jealousy” to be. The word jealousy can not be made into a plural noun by adding an “s”. Therefore, the word “jealousy” is a permanent state of being that can’t be counted.