'case-based' originates from two elements: 'case' and 'based'. 'case' originates from Old French, specifically the word 'cas', from Latin 'casus', where 'cas-' meant 'an event, fall, or occurrence'. 'based' comes from 'base', which originates from Old French 'base', ultimately from Greek 'basis' via Latin, where 'basis' meant 'foundation or pedestal'.

'case' changed from Latin 'casus' to Old French 'cas' and then to Middle English 'cas(e)' before becoming modern English 'case'. 'base' came from Greek 'basis' to Latin 'basis', then Old French 'base', and Middle English 'base'. The compound adjective 'case-based' formed in modern English by joining 'case' + past participle 'based' to mean 'founded on cases or instances'.

Initially, the components referred separately to 'an event/instance' (case) and 'foundation' (base). Over time, the compound evolved to mean 'founded on or determined by particular cases' rather than a general theory.