Noun

Nouns are LRUs used to name a person, place, thing, quality, or action and that can function as the subject or object of a verb, the object of a preposition, or an appositive.

Natural language

In the UNL^arium framework, nouns are classified in two different categories:

• Common nouns (NOU) describe a class of entities (such as "city", "planet", "person", "language", etc);
• Proper nouns (PPN) represent unique entities (such as "London", "Jupiter", "Johnny", "English", etc).

In languages such as English, the difference between common nouns and proper nouns is usually marked by capitalization:

• God, in upper case, is used for representing a unique entity (i.e., a proper noun), while
• god, in lower case, is used to describe a class of entities (a common noun).

Spelling, however, is sometimes misleading:

• Japanese and Shakespereans, for instance, are used to describe a class rather than a unique entity; while
• earth is used for representing a unique entity (the planet we live in).

UNL

In UNL, nouns are always represented by UWs.

• Common nouns are always represented as regular UWs, to be included in the UNL Dictionary and defined in the UNL KB.
• Proper nouns may be represented either as regular UWs or as temporary UWs, depending on their relevance. Names of places (such as "United States"), of people ("Jesus Christ"), of brands ("Coca-cola"), of books ("Romeo and Juliet"), of newspapers ("The New York Times"), of paintings ("La Gioconda"), of songs ("Clair de Lune"), of movies ("Gone with the wind") etc. are to be represented as regular UWs only if normally described in ordinary encyclopaedias.