a tube-shaped sac attached to and opening into the lower end of the large intestine in humans and some other mammals. In humans the appendix is small and has no known function, but in rabbits, hares, and some other herbivores it is involved in the digestion of cellulose

I'm merely standing in while Stella is having her appendix out

a section or table of subsidiary matter at the end of a book or document

a list of such activities was published as an appendix to the report

outline answers may be found in Appendix 2