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Synonyms for Barbarous (same or very similar meaning)

WordNet sense 1 ((of persons or their actions) able or disposed to inflict pain or suffering):
brutal, cruel, fell, roughshod, savage, vicious

WordNet sense 2 (lacking and reflecting lack of pity or compassion):

WordNet sense 3 (not having a high state of culture and social development):
noncivilised, noncivilized

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