The simplest definition of a noun is that it is a word that refers to a person (such as John or teacher), thing (such as ball or table), place (such as Harvard or university), or idea (such as love or emotion).
Some nouns can be counted and they are called countable nouns. Some nouns cannot be counted and they are called uncountable nouns.
Names of people, places, and things are called proper nouns. They always begin with capital letters. All other nouns are common nouns. noncount-nouns.html
Words such as family, team or bunch are collective nouns. They can be used with either a singular or a plural verb.
Abstract and Concrete Nouns
If your five physical senses (sight, smell, hearing, taste, and touch) cannot detect something, it is an abstract noun.
In some languages, nouns refer to specifically to males or females.
A compound noun is made up of two or more words and functions as a noun. The meaning of the compound noun is often different from the meaning of its individual parts.
A verbal noun is a noun formed from a verb but acting as a noun.