'repellence' originates from Latin, specifically the word 'repellere', where the prefix 're-' meant 'back' and 'pellere' meant 'to drive'.

'repellere' passed into Late Latin/Medieval Latin and influenced Old French and Middle English forms (such as 'repelen'/'repel'), and the modern English noun 'repellence' developed from these roots and the noun-forming suffix '-ence'.

Initially it meant 'to drive back' (an action); over time this developed into the noun sense 'the act or quality of driving back' and the specific sense 'effectiveness at repelling' (e.g., insects or moisture).