'conventionally-used' originates from 'convention,' which comes from Latin, specifically the word 'conventio,' where 'con-' meant 'together' and 'venire' meant 'to come.'

'conventio' transformed into the Old French word 'convention,' and eventually became the modern English word 'convention' through Middle English.

Initially, it meant 'a coming together or meeting,' but over time it evolved into its current meaning of 'a customary way of doing things.'