{ En*cy`clo*pe"di*a, En*cy`clo*pæ"di*a } (?), n. [NL., fr. Gr. &?;, for &?; &?;, instruction in the circle of arts and sciences: cf. F. encyclopédie. See Cyclopedia, and Encyclical.] [Formerly written encyclopædy and encyclopedy.] The circle of arts and sciences; a comprehensive summary of knowledge, or of a branch of knowledge; esp., a work in which the various branches of science or art are discussed separately, and usually in alphabetical order; a cyclopedia.

• A comprehensive reference work containing in-depth (usually) articles on a wide range of topics. Some encyclopedias are intended to convey general knowledge, while others focus on one discipline, subject, nationality or ethnicity. Since the 18th century, always arranged in some systematic order, usually alphabetical. Encyclopedias are often in several volumes (if printed), and contain many millions of words, as well as illustrations, maps, and statistics.