A noun is the name of a person, place, thing, or idea. There are several types of nouns including common, proper, abstract, concrete, countable, uncountable, compound, collective, singular, plural, and possessive nouns. Nouns can be used as subjects, predicate nouns, appositives, direct objects, indirect objects, objects of prepositions, object complements, and to show possession. Some nouns are plural in form but singular in meaning, while others are plural in both form and meaning.