Use this domain for general words referring to proper nouns--the name given to a particular person or thing to distinguish it from other things like it. Proper nouns are often not included in a dictionary, or are included in an appendix at the front or back of a dictionary. This is because there are so many of them, they are sometimes difficult to define, and it saves space in the dictionary. For instance place names can be included in a map. So it might be good to type the proper nouns into a special file.