encyclopedia

American  

[en-sahy-kluh-pee-dee-uh] / ɛnˌsaɪ kləˈpi di ə /

Sometimes encyclopaedia

noun

1. a book, set of books, optical disc, mobile device, or online informational resource containing articles on various topics, usually in alphabetical arrangement, covering all branches of knowledge or, less commonly, all aspects of one subject.

2. Encyclopedia, the French work edited by Diderot and D'Alembert, published in the 18th century, distinguished by its representation of the views of the Enlightenment.

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encyclopedia British  

/ 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

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Etymology

Origin of encyclopedia

First recorded in 1525–35; from New Latin encyclopaedia, from Greek enkyklopaidía, a misreading of enkýklios paideía “circular (i.e., well-rounded) education”; see encyclical, pedo- ¹

Explanation

An encyclopedia is a reference work designed to cover all branches and topics of knowledge. We might describe someone who seems to know everything as a "walking encyclopedia." Encyclopedia comes the Greek words for "comprehensive" (cyclo) and "education" (pedia). The first encyclopedias were books (usually in many volumes), but now we have online and electronic encyclopedias. This reference is usually organized alphabetically and covers as many topics as possible. If you're doing research, the encyclopedia is a good place to start.

Example Sentences

In his words: "They showed us a whole encyclopedia of movement and positioning in football."

From BBC • Apr. 15, 2026

He’s like an encyclopedia when it comes to fashion.

From Los Angeles Times • Feb. 14, 2026

To say that “On the Altar” functions more like an encyclopedia than a monograph may sound like criticism.

From The Wall Street Journal • Jan. 25, 2026

He maybe saw the idea of an A.I.-generated encyclopedia and wanted to be first to market.

From Slate • Nov. 17, 2025

His biography in the Suda, a Byzantine encyclopedia dating from the tenth century ce, states that Eratosthenes’ father was named either Aglaos or Ambrosios.

From "Circumference" by Nicholas Nicastro