na-adjective
bestial; beastly; brutal
Describes behavior, instincts, or nature that is animal-like, cruel, or lacking human reason. Often carries a negative, dehumanizing connotation.
彼の獣的な行動に周囲は引いていた。
People around him were put off by his bestial behavior.
戦争は人間の獣的な一面を露わにする。
War exposes the beastly side of human nature.
Compound of 獣 (beast) + 的 (-like, -ish). The suffix 的 is productive for forming adjectival nouns from nouns.