en·cy·clo·pe·di·a 
(ĕn-sī′klə-pēdē-ə)
(ĕn-sī′klə-pēdē-ə)n.
A comprehensive reference work containing articles on a wide range of subjects or on numerous aspects of a particular field, usually arranged alphabetically.
[Medieval Latin encyclopaedia, general education course, from alteration of Greek enkuklios paideia, general education : enkuklios, circular, general; see ENCYCLICAL + paideia, education (from pais, paid-, child; see pau-1 in the Appendix of Indo-European roots).]