'balefulness' originates from Old English, specifically the word 'bāl' (also spelled 'bale'), where 'bāl' meant 'evil, misfortune, harm'; the modern noun is built from the adjective 'baleful' (bale + -ful) with the noun-forming suffix '-ness'.

'balefulness' changed from Middle English forms such as 'balefulnesse' (from 'bale' + '-ful' + '-nesse') and eventually became the modern English word 'balefulness'.

Initially it meant 'the state or condition of causing harm or misfortune', and over time it has retained that core sense while also coming to be used for a more general 'ominous or threatening quality'.