1. The written circle of learning; a general course of instruction: An encyclopedia is a literary work containing extensive information about all branches of knowledge which are normally arranged in alphabetical order.
2. An elaborate and exhaustive repertory of information on all the branches of some particular art or department of knowledge: Albert's teacher told her students that they could find lots of information for their projects in encyclopedias at the local library.
3. Etymology: from Greek egkukiopaideia, "general education"; from egkuklios, "general" + paideia, "education"; from pais, "boy, child"; however, literally "training in a circle" from enkyklios, "circular" + paideia, "education, child-rearing", from pais, "boy, child".

The term encyclopedia is said to be an erroneous form (a false reading) occurring in manuscripts of Quintilian, Pliny, and Galen, for "encyclical education", the circle of arts and sciences considered by the Greeks as essential to a liberal education.