appendix

noun

ap·​pen·​dix ə-ˈpen-diks 

plural appendixes or appendices ə-ˈpen-də-ˌsēz 

1

a

: appendage

b

: supplementary material usually attached at the end of a piece of writing

The book's appendix includes a bibliography.

2

: a bodily outgrowth or process

specifically : vermiform appendix

Synonyms of appendix

• epilogue
• supplement
• documentation
• afterword
• addition
• addendum
• codicil
• conclusion

Examples of appendix in a Sentence

In your textbooks, turn to Appendix 3: Glossary of Terms.

The book has several appendixes.

Recent Examples on the Web

Peter the Great’s dream The Sea of Azov is an inland sea that sits between the southern shores of Ukraine and Russia, a kind of an appendix to the bigger Black Sea. — Ivana Kottasová, CNN Money, 15 July 2026

The film’s story, much of it developed from Tolkien’s appendices, is set between The Hobbit and The Fellowship of the Ring. — Tom Tapp, Deadline, 14 July 2026

In 2012, after losing his job, his girlfriend, and his appendix following an emergency appendectomy, Mark Fischbach was seeking solace. — Shannon Carlin, Time, 14 July 2026

Not because a new appendix deserves a barnstorming tour, or because county unemployment data has suddenly become beach reading. — Andrew Leahey, Forbes.com, 29 June 2026

Word History

Etymology

borrowed from Latin appendic-, appendix "something subordinate or supplementary attached to a larger unit," fr. appendere, presumably "to attach to something larger by hanging " + -ic-, -ix, noun suffix — more at append

Note: Regarding the meaning of appendere see note at append.

First Known Use

1549, in the meaning defined at sense 1b

Phrases Containing appendix

• vermiform appendix

Kids Definition

appendix

noun

ap·​pen·​dix ə-ˈpen-diks 

plural appendixes or appendices -də-ˌsēz 

1

: additional material attached at the end of a piece of writing

2

: a small tube that is closed at one end and projects from the pouch marking the beginning of the large intestine in the lower right side of the abdomen

Medical Definition

appendix

noun

ap·​pen·​dix ə-ˈpen-diks 

plural appendixes or appendices -də-ˌsēz 

: a bodily outgrowth or process

specifically : vermiform appendix