'heater' originates from the Old English word 'hǣtan,' where 'hǣtan' meant 'to heat.'

'hǣtan' transformed into the Middle English word 'heten,' and eventually became the modern English word 'heat,' from which 'heater' is derived.

Initially, it meant 'to make hot,' and over time it evolved into its current meaning of 'a device that produces heat.'