'appendix' originates from Latin, specifically the word 'appendix' (from the verb 'appendere'), where 'ad-' meant 'to' and 'pendere' meant 'to hang', giving the sense 'something hung on'.

'appendix' changed from Late Latin 'appendix' (and verb 'appendere') into Middle English as 'appendix' and eventually became the modern English word 'appendix'.

Initially, it meant 'something hung on' or 'an attachment', but over time it evolved into its current meanings of 'a supplementary section at the end of a book' and the anatomical 'vermiform appendix'; by extension it also conveys the idea of something 'attached' or 'added'.