'backflowing' originates from English, specifically the compound 'backflow' plus the suffix '-ing', where 'back' meant 'rear' or 'backward' and 'flow' meant 'to move in a stream.'

'back' comes from Old English 'bæc' and 'flow' from Old English 'flowan'; these elements combined into the Modern English compound 'backflow', and the present-participle form 'backflowing' was formed by adding the suffix '-ing'.

Initially it meant 'a flow toward the back or in reverse'; over time the meaning has remained largely the same and is used to indicate movement or movement-causing events in the reverse direction ('flowing backward').