'deflectable' originates from Latin, specifically the word 'deflectere', where the prefix 'de-' meant 'away, off' and 'flectere' meant 'to bend'.

'deflectere' passed into later Latin and influenced Old French/Medieval usage (e.g. early forms like 'deflecter'), then entered English as the verb 'deflect'. The adjective was formed in English by adding the suffix '-able' to produce 'deflectable'.

Initially related to the literal sense 'to bend or turn away', the sense broadened to include figurative meanings like turning aside attention or criticism; the adjective now commonly means 'capable of being turned aside' in both physical and figurative contexts.