'customarily-used' originates from the word 'customary,' which comes from the Latin word 'consuetudinarius,' where 'consuetudo' meant 'habit or custom.'

'customarily' evolved from the Old French word 'costumier,' which eventually became the modern English word 'customary.'

Initially, it meant 'according to custom,' but over time it evolved into its current meaning of 'commonly used.'