'natural' originates from Latin, specifically the word 'naturalis' (from 'natura'), where 'natura' meant 'birth, quality, or course of things'; 'cause' originates from Latin, specifically the word 'causa', which meant 'a cause, reason, or legal case.'

'natural cause' is a compound of Middle English and Latin-derived vocabulary: 'natural' (from Old French/Latin via Middle English) combined with 'cause' (from Old French 'cause' < Latin 'causa') to form the modern phrase 'natural cause(s)'.

Initially, 'natural' and 'cause' separately carried meanings related to nature and reason; together as the phrase 'natural cause(s)' it came to be used especially in medical and legal contexts to denote death or events owing to natural processes rather than external or criminal actions.