'incidental' originates from Medieval Latin, specifically the word 'incidentalis,' where 'incidere' meant 'to fall upon.'

'incidentalis' transformed into the Old French word 'incidentel,' and eventually became the modern English word 'incidental' through Middle English.

Initially, it meant 'falling upon or happening by chance,' but over time it evolved into its current meaning of 'occurring as a minor accompaniment or by chance.'