'barbarousness' originates from English, specifically from the word 'barbarous', which ultimately comes from Latin 'barbarus' and Greek 'barbaros', where 'barbaros' meant 'foreign, not Greek (foreign-sounding)'.

'barbarousness' developed from Middle English 'barbarous' (borrowed via Old French 'barbare' / Latin 'barbarus') and the noun suffix '-ness' was added in English to form 'barbarousness'.

Initially, related forms meant 'foreign' or 'strange' (from Greek 'barbaros'), but over time the sense shifted toward 'uncivilized' or 'savage'; today 'barbarousness' conveys 'cruelty or lack of civilization'.