Appendix \Ap*pen"dix\, n.; pl. E. Appendixes, L. Appendices. [L. appendix, -dicis, fr. appendere. See Append.] 1. Something appended or added; an appendage, adjunct, or concomitant. Normandy became an appendix to England. --Sir M. Hale. 2. Any literary matter added to a book, but not necessarily essential to its completeness, and thus distinguished from supplement, which is intended to supply deficiencies and correct inaccuracies. Syn: See Supplement.