'battery-operated' originates from the combination of 'battery' and 'operate,' where 'battery' refers to a device that stores energy and 'operate' means to function or work.

'battery' comes from the Old French 'batterie,' meaning 'action of beating,' and 'operate' from the Latin 'operari,' meaning 'to work.'

Initially, 'battery' referred to a group of artillery guns, but over time it evolved to mean a device that stores electrical energy.