A comprehensive reference book or collection of information covering a wide range of subjects, also spelled encyclopedia.
From Greek kyklo- (circle, all-around) + paideia (education, instruction). The word literally means 'all-around education' and emerged in the 18th century as comprehensive knowledge collections became popular.
The most famous cyclopaedia was Diderot's 18th-century French Encyclopédie, which was so radical it was banned—knowledge itself was considered dangerous to authorities.
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