'error-free' originates from the combination of 'error' and 'free', where 'error' meant 'a mistake' and 'free' meant 'without'.

'error' changed from the Old French word 'errur' and eventually became the modern English word 'error'.

Initially, 'error' meant 'a wandering or straying', but over time it evolved into its current meaning of 'a mistake'.