'indexer' originates from English, specifically from the word 'index' plus the agentive suffix '-er', where 'index' comes from Latin 'index' meaning 'one who points out; sign, indicator'.

'indexer' changed from Latin 'index' (via Medieval Latin and Old French forms 'indice'/'index') into Middle English 'index', and the English agent suffix '-er' was added to form the modern English word 'indexer'.

Initially, 'index' meant 'a pointer or sign' in Latin, but over time it evolved into the modern senses of 'a list of topics/entries' and related agent noun 'indexer' meaning 'one who creates or maintains such lists (or the tool that does so)'.