'adventitial' originates from Latin, specifically the word 'adventicius,' where 'ad-' meant 'to' and 'venire' meant 'come.'

'adventicius' transformed into the French word 'adventice,' and eventually became the modern English word 'adventitial' through Middle English.

Initially, it meant 'coming from outside,' but over time it evolved into its current meaning of 'relating to the outermost layer of a structure.'