What does cyclopaedia mean?
A cyclopaedia is a large-scale reference work that assembles knowledge across many fields of study, or treats every facet of a single discipline in depth. The word is essentially a variant — and historically earlier — spelling of 'encyclopaedia', formed from the Greek roots for 'circle' and 'education', evoking the idea of a complete circle of learning. Although modern readers almost always encounter the word as 'encyclopaedia' or 'encyclopedia', 'cyclopaedia' endures in the titles of landmark works of the eighteenth and nineteenth centuries, notably Ephraim Chambers's Cyclopaedia of 1728 and Abraham Rees's Cyclopaedia of the early 1800s, which helped shape the tradition of the modern general reference book. Today the term carries a formal, scholarly flavour and appears mostly in discussions of bibliography, publishing history, and rare books. Knowing it is useful when reading older texts, where it may appear without being a typo.
nounA cyclopaedia is a comprehensive reference work containing articles on a wide range of subjects or on numerous aspects of one subject; it is a chiefly British spelling variant of 'encyclopaedia' (or 'encyclopedia').
- A comprehensive reference work covering all branches of knowledge, or a particular field (a spelling variant and historical form of 'encyclopaedia').
"The scholar spent years compiling a cyclopaedia of early printing techniques."
"Rees's Cyclopaedia, published in the early nineteenth century, contained articles by some of the leading scientists of the day."
"The library's rare-books room holds a leather-bound cyclopaedia from the 1700s."
The plural follows standard English noun pluralisation.
"The auction featured several eighteenth-century cyclopaedias."
Before the word 'encyclopaedia' settled into place, 18th-century scholars like Ephraim Chambers called their great works 'cyclopaedias' — literally 'circles of learning', knowledge arranged in a complete ring.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cyclopaedia
The word derives from the French 'cyclopédie' and ultimately from Greek elements: 'kyklos' (circle) and 'paideia' (education), suggesting a well-rounded course of instruction. It entered English in the seventeenth century as an alternative rendering of the same Greek phrase that also produced 'encyclopaedia'. Both forms coexisted for centuries, but 'encyclopaedia' became the dominant spelling, leaving 'cyclopaedia' as a chiefly historical variant preserved in famous work titles.
Related word forms
How cyclopaedia is actually used
The spelling 'cyclopaedia' is now uncommon; modern usage overwhelmingly prefers 'encyclopaedia' (British) or 'encyclopedia' (US). It survives mainly in historical titles such as Chambers's Cyclopaedia (1728) and Rees's Cyclopaedia. The register is formal and scholarly.
Easily confused with cyclopaedia
'Cyclopaedia' is essentially the same word as 'encyclopaedia', differing only in the initial vowel — both derive from the same Greek roots, and 'cyclopaedia' is now largely an archaic or variant form.