'apprehender' originates from Latin, specifically the word 'apprehendere', where 'ad-' meant 'to' and 'prehendere' (from 'prehendere') meant 'to seize or grasp'.

'apprehender' changed from Latin 'apprehendere' into Old French/Anglo-Norman forms and then into Middle English 'apprehenden' (or similar spellings); the modern English noun 'apprehender' was formed by adding the agentive suffix '-er' to the verb 'apprehend'.

Initially, it meant 'one who seizes or takes hold' (literal sense of seizing); over time it also acquired senses related to 'arresting' (legal sense) and 'understanding' (figurative sense).