Traditionally defined as the part of speech (or word class) that names or identifies a person, place, thing, quality, or activity. Adjective: nominal.
Most nouns have both a singular and plural form, can be preceded by an article and/or one or more adjectives, and can serve as the head of a noun phrase.
A noun or noun phrase can function as a subject, direct object, indirect object, complement, appositive, or object of a preposition. In addition, nouns sometimes modify other nouns to form compound nouns. (See Examples and Observations, below.)