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

Three years before the ACA was implemented, in 2007, Eugenia Horan's husband's appendix ruptured, and an appendectomy spiraled into a medical emergency when complications set in, leaving the uninsured couple with a $400,000 bill. —Lucy Notarantonio, MSNBC Newsweek, 30 Nov. 2025

Apparently, the chair was missing its appendix, a lever manufactured in Hungary roughly the same shape and size as sticks of an opiate called Thebaine. —Ben Rosenstock, Vulture, 3 Nov. 2025

The suit does not include an appendix showing the analysis, doesn’t say who conducted it, and NBC News could not independently verify the findings. —Lauren Wilson, NBC news, 3 Nov. 2025

Kraus ends with an appendix of messages the murderers exchanged leading up to the crime…These texts are not rich text. —Literary Hub, 23 Oct. 2025

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