a reference work (often in several volumes) containing articles on various topics (often arranged in alphabetical order) dealing with the entire range of human knowledge or with some particular specialty
"During my research project, I consulted every volume of the Britannica encyclopaedia to gather comprehensive information on renewable energy."
Alternative spelling of encyclopedia
"My grandfather spent his retirement years meticulously typing out an encyclopaedia on local history before digitizing it for the school archive."
The word entered English as a borrowing from New Latin, where it originally meant "a circle of learning." The modern spelling with a 'p' was later adopted to align with the Greek roots of the term.