en·cy·clo·pe·di·a  (?n-s??kl?-p??d?-?)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- in Indo-European roots).]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.encyclopedia (?n?sa?kl???pi?d??) or encyclopaedian (Journalism & Publishing) a book, often in many volumes, containing articles on various topics, often arranged in alphabetical order, dealing either with the whole range of human knowledge or with one particular subject: a medical encyclopedia. [C16: from New Latin encyclopaedia, erroneously for Greek enkuklios paideia general education, from enkuklios general (see encyclical), + paideia education, from pais child]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014en?cy?clo?pe?di?a or en?cy?clo?pae?di?a (?n?sa? kl??pi di ?) n. a book or set of books containing articles on various topics, usu. in alphabetical arrangement, covering all branches of knowledge or all aspects of one subject. [1525?35;