A noun that refers to a unique individual, place or organization. During early childhood, children learn the meanings of proper and common nouns and the syntactical difference between them. There is longstanding evidence that children first discriminate among individuals and learn how to name them, but for other classes of objects (e.g., toys) they first learn names only for a class. In doing so, they acquire the ability to distinguish between the two types of nouns.
See Count (or countable) noun, Language development, Open-class words