A noun, or noun substantive, is a part of speech (a word or phrase) which can co-occur with (in)definite articles and attributive adjectives, and function as the head of a noun phrase. The word "noun" derives from the Latin 'nomen' meaning "name", and a traditional definition of nouns is that they are all and only those expressions that refer to a person, place, thing, event, substance, quality, idea or an appointment. They serve as the subject or object of a verb, and the object of a preposition. (http://en.wikipedia.org/wiki/Noun 19.09.06)