'affiliation' originates from Medieval Latin, specifically the word 'affiliatio,' where 'ad-' meant 'to' and 'filiare' meant 'to adopt as a son.'

'affiliatio' transformed into the French word 'affiliation,' and eventually became the modern English word 'affiliation' through Middle English.

Initially, it meant 'to adopt as a son,' but over time it evolved into its current meaning of 'association or connection with a group or organization.'