noun, na-adjective
primitive and barbarous; uncivilized and barbaric
Describes a state of being both uncivilized and cruel; often used in historical or anthropological contexts. Can also be used figuratively to criticize behavior as savage.
その部族は未開野蛮な生活を送っていた。
The tribe led a primitive and barbarous life.
彼の行動は未開野蛮で、許しがたい。
His behavior was uncivilized and barbaric, and unforgivable.
Compound of 未開 (primitive, uncivilized) and 野蛮 (barbaric, savage). The exact historical derivation is uncertain, but the combination intensifies the meaning of both components.