'impeachableness' originates from English, formed from the verb 'impeach' plus the adjective-forming suffix '-able' and the noun-forming suffix '-ness'. The verb 'impeach' itself comes from Old French 'empechier', ultimately from Latin roots related to 'impedire'/'impedicare', where the element related to 'ped-' meant 'foot' (originally with the sense of entangling or hindering).

'impeach' passed into Middle English from Old French 'empechier' (to hinder); over time the sense shifted in English from 'to hinder' to 'to accuse (a public official)'. The adjective 'impeachable' (capable of being impeached) was formed from 'impeach' + '-able', and the abstract noun 'impeachableness' was later formed by adding '-ness'.

Initially 'empechier' and early forms of 'impeach' carried the sense 'to hinder' or 'to entangle'; in English the meaning shifted toward formally accusing or charging (especially public officials), and 'impeachableness' now denotes the capacity or fitness for such an accusation.