encyclopedia

American  

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

Sometimes encyclopaedia

noun

encyclopedias plural

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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Other Word Forms

Noun Inflected Forms

• encyclopedias
  plural

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

See Examples For:

encyclopedia encyclopedias

A boom in artificial intelligence is deepening a crisis in trust across society, according to the co-founder of online encyclopedia Wikipedia.

From The Wall Street Journal ● Jun. 10, 2026

Did everyone routinely use the encyclopedia, or read the Steinbeck novel, or listen attentively to Schubert’s Unfinished Symphony?

From Salon ● Apr. 19, 2026

As a child, he came across a page in an encyclopedia featuring Neil Armstrong and the picture of an astronaut on the Moon from the 1969 Apollo mission.

From BBC ● Apr. 2, 2026

The decision arrives not a moment too soon for the online encyclopedia, which has seen a deluge of hallucination-prone A.I.-written articles since ChatGPT’s launch.

From Slate ● Apr. 1, 2026

Then he rose again, went into the den, and returned carrying several volumes of an outdated encyclopedia.

From "The Mysterious Benedict Society" by Trenton Lee Stewart

Physical encyclopedias and textbooks were rendered virtually useless.

From Salon ● May 30, 2026

“My father filled my head with stories” about the “pioneer nurseryman,” Mr. Fitzgerald recalls, “while my mother brought me dusty encyclopedias full of primary sources.”

From The Wall Street Journal ● May 26, 2026

Samantha said Max has watched all of Sir David's documentaries and owns more animal encyclopedias than she can keep track of.

From BBC ● May 7, 2026

They’re both walking encyclopedias of the genre, able to reel off titles of films, popular and obscure, with the alacrity of true aficionados.

From Los Angeles Times ● Apr. 16, 2024

The answer can usually be found in the dictionary or in the old set of encyclopedias that are in our living room bookcase.

From "Doing Time Online" by Jan Siebold