'baddishness' originates from English, specifically from the adjective 'baddish' (formed from 'bad' + the suffix '-ish'), where 'bad' meant 'of poor quality or morally wrong' and the suffix '-ish' meant 'having the quality of'.

'baddishness' developed by combining the long-established English adjective 'bad' (attested in Middle English as 'bad') with the Old English/Old Germanic-derived suffix '-ish' (from Old English '-isc') to form 'baddish', and then adding the noun-forming suffix '-ness' (from Old English '-nes') to create the modern derived noun 'baddishness'.

Initially, 'bad' primarily referred to poor quality or wickedness; over time the derived combination produced a noun meaning 'the quality of being somewhat bad'—often less strong than 'badness' and sometimes carrying a nuance of affectation.