A noun is a word that refers to a person, a thing, a place, or an idea.
In Biblical Hebrew, all nouns contain number, gender, state, and definiteness. By number, a noun can be singular, plural, or dual. By gender, a noun can be masculine or feminine. By state, a noun can be in the construct state or in the absolute state. Nouns are listed in a Hebrew dictionary by their singular absolute form. Also, a variety of prefixes and/or suffixes can be attached to nouns that give extra information.
Sometimes the actual classification of a noun does not match its form. For example, a noun can appear dual when it is actually plural; a noun can appear masculine when it is actually feminine; and so on.
In Biblical Hebrew, it is very common for words to change their function within a sentence. For example, adjectives, and participles (both active and passive) often function as nouns. Also, sometimes a noun can function as an adverb or a preposition.