'illustration' originates from Latin, specifically the word 'illustratio,' where 'illustratus' meant 'to make bright or clear.'

'illustratio' transformed into the Old French word 'illustracion,' and eventually became the modern English word 'illustration' through Middle English.

Initially, it meant 'to make something clear or bright,' but over time it evolved into its current meaning of 'a picture or example that explains something.'