'backlash' originates from English, specifically the compound 'back' + 'lash', where 'back' meant 'the rear' or 'back' and 'lash' meant 'to strike' or 'a blow'.

'backlash' originally described a mechanical recoil or backward movement (mid–19th century usage) and later (20th century) evolved into a figurative sense referring to a strong adverse reaction in social or political contexts.

Initially, it meant 'a backward movement or recoil,' but over time it evolved into its current meaning of 'a strong adverse reaction or public opposition.'