A noun is a word that functions as the name of some specific thing or set of things, such as living creatures, objects, places, actions, qualities, states of existence, or ideas.

A noun is a part of speech that  can occur as the main word in the subject of a clause, the object of a verb, or the object of a preposition. They can be modified using an adjective or an adjective phrase.

In some languages, nouns can be grouped together in a noun class . They can often be marked for number (e.g., singular and plural)

Reference: noun