Definition: "Appendix" refers to a section or part added at the end of a book or document, often used for extra information that might not fit into the main text but could be relevant in another context. The term comes from Latin "appenditus," which literally means 'added text' and was first used in the 17th century. It's an essential element in many academic works to add supplementary information or corrections, often in the form of notes, footnotes, or annotations.