encyclopedia

UK: /ɪnˌsaɪkləˈpiːdiə/

US: /ɛnˌsaɪkləˈpidiə/

US: (en sī′klə pē′dē ə)

WordReference Random House Learner's Dictionary of American English © 2025

en•cy•clo•pe•di•a or en•cy•clo•pae•di•a/ɛnˌsaɪkləˈpidiə/   n. [countable] , pl. -dias. 

1. Literature a book or set of books containing articles on various topics, usually in alphabetical arrangement, covering all branches of knowledge or all aspects of one subject.

en•cy•clo•pe•dic, adj. See -cycle-, -ped-².

WordReference Random House Unabridged Dictionary of American English © 2025

en•cy•clo•pe•di•a  (en sī′klə pē′dē ə), n. 

1. Literature a book or set of books containing articles on various topics, usually in alphabetical arrangement, covering all branches of knowledge or, less commonly, all aspects of one subject.
2. Literature (cap.) the French work edited by Diderot and D'Alembert, published in the 18th century, distinguished by its representation of the views of the Enlightenment.

Also, en•cy′clo•pae′di•a. 

• Greek enkyklopaidía, a misreading of enkýklios paideía circular (i.e., well-rounded) education. See encyclical, pedi-²
• Neo-Latin encyclopaedia
• 1525–35

Collins Concise English Dictionary © HarperCollins Publishers::

encyclopedia, encyclopaedia / ɛnˌsaɪkləʊˈpiːdɪə/ noun

1. 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

Etymology: 16th Century: from New Latin encyclopaedia, erroneously for Greek enkuklios paideia general education, from enkuklios general (see encyclical), + paideia education, from pais child