'includer' originates from Latin, specifically the word 'includere', where 'in-' meant 'in/into' and 'claudere' (from which 'clud-' derives) meant 'to shut/close'.

'includer' changed from Old French 'inclure' and Middle English 'include', and the modern English agentive form was formed by adding the suffix '-er' to 'include' to make 'includer'.

Initially, the verb 'includere' meant 'to shut in or enclose', but over time it evolved into the sense 'to make part of or contain'; the noun 'includer' now means 'one that includes or contains'.