'backrest' originates from English, specifically formed from the Old English elements 'bæc' and 'ræst', where 'bæc' meant 'back' and 'ræst' meant 'rest/place of repose'.

'backrest' appeared in Middle English in compound forms such as 'bakrest' or 'backrest' and eventually became the modern English word 'backrest'.

Initially, it meant 'a place for the back to rest' and this basic sense has remained stable into the current meaning of 'the part of a seat that supports the back'.