Final answer:
A noun is a part of speech that names a person, place, thing, or idea.
Step-by-step explanation:
A part of speech that names a person, place, thing, or idea is called a noun. Nouns are one of the basic building blocks of sentences and serve as the subjects or objects of verbs. For example, in the sentence 'John is reading a book,' 'John' and 'book' are both nouns.
Learn more about Parts of Speech