'accidency' originates from Latin, specifically the word 'accidentia,' where 'accidens' meant 'happening' or 'occurrence.'

'accidentia' transformed into the Old French word 'accidencie,' and eventually became the modern English word 'accidency.'

Initially, it meant 'a happening or occurrence,' but over time it evolved into its current meaning of 'a non-essential quality or feature.'