An encyclopedic dictionary typically includes many short listings, arranged alphabetically, and discussing a wide range of topics. Encyclopedic dictionaries can be general, containing articles on topics in many different fields; or they can specialize in a particular field, such as art, biography, law, medicine, or philosophy. They may also be organized around a particular academic, cultural, ethnic, or national perspective.
Historically, the term has been used to refer to any encyclopedic reference book (that is, one comprehensive in scope), which was organized alphabetically, as with the familiar dictionary (the term dictionary preceded encyclopedia in common usage by about two centuries). To convey their alphabetic method of organization and to contrast that method with other systems for classifying knowledge, many early encyclopedias were titled or sub-titled "a dictionary of arts and sciences" or something similar.