'backslide' originates from Old English elements: specifically Old English 'bæc' and Old English 'slīdan', where 'bæc' meant 'back' and 'slīdan' meant 'to glide or slip'.

'backslide' developed in Middle English from compound forms meaning 'to slide back' (e.g. Middle English compounds built from 'bak' + 'sliden') and eventually became the modern English verb 'backslide'.

Initially it meant 'to slide or move backward', but over time it evolved into its current meaning of 'to lapse or relapse into a former (usually worse) condition or behavior', especially moral or religious relapse.