'repellent' originates from Latin, specifically the word 'repellens', present participle of 'repellere', where 're-' meant 'back' and 'pellere' meant 'to drive'.

'repellens' (Latin) passed into Late Latin and influenced Old French and Middle English forms; Middle English adopted the word as 'repellent' from these Latin/French influences and it became the modern English 'repellent'.

Initially, it meant 'driving back' or 'pushing away' (literal sense from Latin); over time it came to refer both to things that physically repel (e.g., insects, water) and to qualities that cause aversion (i.e., 'repellent' meaning disgusting).