'disease-causing' originates from the combination of 'disease' and 'cause', where 'disease' meant 'a disorder of structure or function' and 'cause' meant 'to make something happen'.

'disease' changed from the Old French word 'desaise' and 'cause' from the Latin word 'causa', eventually forming the modern English term 'disease-causing'.

Initially, 'disease' meant 'discomfort' and 'cause' meant 'reason', but over time they evolved into their current meanings of 'illness' and 'to bring about', respectively.