Simple Definition:

A noun is a word that represents a person, place, thing, or idea.

Examples:

• Person: John, teacher, friend
• Place: New York, beach, park
• Thing: car, book, table
• Idea: love, happiness, freedom

Very Simple Definition:

A noun is a word for a person, place, thing, or idea.

Examples:

• Person: John, teacher, friend
• Place: New York, beach, park
• Thing: car, book, table
• Idea: love, happiness, freedom