'reservedly' originates from the Latin word 'reservare,' where 're-' meant 'back' and 'servare' meant 'to keep.'

'reservare' transformed into the Old French word 'reserver,' and eventually became the modern English word 'reserve' through Middle English.

Initially, it meant 'to keep back or save,' but over time it evolved into its current meaning of 'in a restrained manner.'