What does encyclopaedia mean?
An encyclopaedia is a comprehensive reference work that gathers authoritative information across many fields of knowledge — or across every aspect of a single subject — usually organized alphabetically by topic. Traditionally published as large multi-volume sets, encyclopaedias today are just as likely to exist online, where entries can be updated continuously. The word derives from Greek roots meaning roughly 'circle of learning,' capturing the ambition to encompass all human knowledge within a single work. Beyond its literal sense, encyclopaedia is used figuratively to describe a person of unusually broad learning, as in 'a walking encyclopaedia.' Both British spelling ('encyclopaedia', with the 'ae') and American spelling ('encyclopedia') are widely accepted. Whether consulted for a school project or admired as a monument to collective scholarship, the encyclopaedia remains one of the most enduring formats for organizing and sharing what humanity knows.
A comprehensive reference work — traditionally a multi-volume set of books, now often digital — containing detailed articles on all branches of knowledge, or on every aspect of a particular field, typically arranged alphabetically.
"He consulted the encyclopaedia to verify the dates of the Napoleonic Wars before submitting his essay."
(Figurative) A person or resource regarded as having exceptionally wide-ranging knowledge.
"My grandfather was a walking encyclopaedia of local history and could name every farm in the valley."
Almost always used with modifiers such as 'walking', 'living', or 'a veritable' when applied to people.
The regular plural simply adds -s; spelling follows whichever variant (ae vs. e) the writer adopts.
"The second-hand shop had several old encyclopaedias stacked in the corner."
The word 'encyclopaedia' comes from a Greek phrase meaning 'the circle of learning' — the idea that all knowledge forms one complete ring.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of encyclopaedia
The word encyclopaedia entered English in the early modern period, derived from the Greek enkuklios paideia, meaning 'general education' or literally 'circular (i.e., well-rounded) instruction.' A Renaissance-era misreading of the Greek phrase as enkyklopaidia ('circle of learning') gave rise to the modern form. It shares its Greek root with words like cycle (from kyklos, 'circle') and is cognate with pedagogy (from paideia, 'education'). The variant spelling cyclopaedia also appeared in English during the seventeenth century.
Related word forms
How encyclopaedia is actually used
Both spellings 'encyclopaedia' and 'encyclopedia' are correct: the 'ae' form reflects the Greek diphthong and is standard in British English, while 'encyclopedia' dominates American English. The word carries a slightly formal register but appears freely in everyday speech, especially in figurative uses like 'a walking encyclopaedia'. In modern usage it often evokes digital resources such as Wikipedia as much as traditional multi-volume print sets.
Easily confused with encyclopaedia
An encyclopaedia provides in-depth articles on subjects and concepts, whereas a dictionary defines individual words and their meanings.
An atlas is a collection of maps; an encyclopaedia is a general reference work covering knowledge in prose articles.