A word that names a person, place, or thing is a noun. Nouns can identify physical objects such as "table," living beings such as "teacher," places such as "London," or abstract ideas such as "freedom."
Nouns commonly serve as the subject or object of a sentence and can act as the head of a noun phrase. In English, they often combine with determiners, including "a," "the," and "this," as well as adjectives: "the old bridge." Nouns may be common, such as "river," or proper, such as "Nile."
The traditional definition is useful but not complete. Nouns can also name actions, events, qualities, and states, including "arrival," "beauty," and "sleep." They are different from verbs, which typically express actions or states, and from pronouns, which stand in for noun phrases. Linguists classify nouns partly by how they behave in sentences, and definitions vary somewhat across languages.