Appendence is a term that refers to something that is added or attached to a larger or more fundamental structure. Synonyms that can be used in place of this term include adjunct, attachment, supplement, addendum, annex, extension, and appurtenance. Each of these words implies a sense of something extra or secondary that is tacked on to something else. Whether it is a document or a body part, an appendence is always something that is in some way secondary to the primary object, but still important in its own right. Using synonyms like these can help to add variety and depth to your writing, while also making it easier to communicate complex ideas.