An encyclopedia (or encyclopædia) is a comprehensive written compendium that contains information on either all branches of knowledge or a particular branch of knowledge. Encyclopedias are divided into articles with one article on each subject covered. The articles on subjects in an encyclopedia are usually accessed alphabetically by article name and can be contained in one volume or many volumes, depending on the amount of material included.

Etymology, Spelling

The word 'encyclopedia' comes from the Classical Greek (pronounced "enkyklios paideia"), literally, a "1rounded education", meaning "general knowledge". Though the notion of a compendium of knowledge dates back thousands of years, the term was first used in the title of a book in 1541 by Joachimus Fortius Ringelbergius, Lucubrationes vel potius absolutissima kyklopaideia (Basel, 1541). The word encyclopaedia was first used as a noun in the title of his book by the Croatian encyclopedist Pavao Skalić in his Encyclopaedia seu orbis disciplinarum tam sacrarum quam prophanarum epistemon (Encyclopaedia, or Knowledge of the World of Disciplines, Basel, 1559). One of the oldest vernacular uses was by François Rabelais in his Pantagruel in 1532.

Several encyclopedias have names that include the suffix -p(a)edia, e.g., Banglapedia (on matters relevant for Bengal).

In British usage, the spellings encyclopedia and encyclopaedia are both current; in American usage, only the former is commonly used. The spelling encyclopædiawith the æ ligaturewas frequently used in the 19th century and is increasingly rare, although it is retained in product titles such as Encyclopædia Britannica and others. The Oxford English Dictionary (1989) records encyclopædia and encyclopedia as equal alternatives (in that order), and notes the æ would be obsolete except that it is preserved in works that have Latin titles. Webster's Third New International Dictionary (1997–2002) features encyclopedia as the main headword and encyclopaedia as a minor variant. In addition, cyclopedia and cyclopaedia are now rarely-used shortened forms of the word originating in the 17th century.

Characteristics

To address those needs, an encyclopedia treats each subject in more depth and conveys the most relevant accumulated knowledge on that subject or discipline, given the overall length of the particular work. An encyclopedia also often includes many maps and illustrations, as well as bibliography and statistics. Historically, both encyclopedias and dictionaries have been researched and written by well-educated, well-informed content experts.