PROPER NOUN. A category of NOUN, distinguished on grammatical and semantic grounds from COMMON NOUN, and written with a CAPITAL letter. Proper nouns are primarily NAMES of persons (John, Churchill), places (India, Edinburgh), and various periods of time (Sunday, August). Their reference is said to be unique in context and definite; sometimes the is used with the noun (The Hague), but most names are definite without requiring the definite article. Grammatically, indefinite a/an and most other determiners are not used with proper nouns, nor is there normally a singular/plural contrast: (Mount) Kilimanjaro, the Seychelles, but not *a Kilimanjaro, *a Seychelle. There is, however, no clear demarcation between proper and common nouns, regardless of the initial capital. People can speak of Churchills, who could be members of the Churchill family, people with that surname, or people figuratively compared to Winston Churchill. There might be a different Churchill (not Winston), a Sunday in June, that memorable August, the Edinburgh of her childhood, and so on. Here, for specific purposes, proper nouns have effectively been converted into common nouns. Common nouns can also on occasion behave like proper nouns, as in: I do not fear you, Death. Nationality nouns (Americans, a New Zealander, the Japanese) lie on the borderline between proper and common nouns. Some grammarians distinguish the proper noun (a single noun like London; the and a single noun: the Pennines) from the proper name, a wider category which includes these and also such word groups as the United States (of America), the Houses of Parliament, the Royal Navy, A Tale of Two Cities, The Concise Oxford Dictionary.

prop·er noun (also proper name) • n. a name used for an individual person, place, or organization, spelled with initial capital letters, e.g., Larry, Mexico, and Boston Red Sox. Often contrasted with common noun.