How to say "vicious" in Japanese

• 悪質あくしつCommon
  na-adjective, nounCovers vicious in the sense of malicious and underhanded: a nasty prank, scam, or hoax done with bad intent. It judges the quality of the act itself as sly and ill-natured rather than violent.
  悪質あくしつなドライバーは免許証めんきょしょうを取り上とりあげるべきだ。↗

  Bad drivers should have their licenses taken away from them.
• 陰湿いんしつCommon
  na-adjective, nounFits vicious as spiteful and insidious — mean-spirited nastiness carried out covertly, behind the scenes, rather than open violence. Think of sly, underhanded bullying or persistent malicious gossip.
  中学ちゅうがく・高校こうこうでは陰湿いんしつないじめが増ふえる傾向けいこうにあるという。↗

  In junior high and high schools, they say insidious forms of bullying are on the rise.
• 凶悪きょうあくCommon
  na-adjective, nounThis is for vicious in the physical, violent sense: atrocious, heinous, brutal acts — savage crimes and fiendish violence. It is not the word for sly or spiteful meanness; use it when vicious means brutal.
  最近さいきんの凶悪きょうあく事件じけんをニュースで見みるたび、バーチャルな世界せかいと生いきる世界せかいの区別くべつがなくなった若者わかものが急増きゅうぞうしていることに気付きづかされる。↗

  These days when I hear about these horrible incidents on the news I get the feeling that more and more young people are losing their ability to distinguish between real and virtual worlds.

Use 悪質 for vicious acts that are malicious and underhanded, 陰湿 for spiteful, insidious meanness, and 凶悪 for vicious violence — brutal, atrocious or heinous behavior rather than sly malice.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 悪質あくしつmalicious
• 陰湿いんしつmalicious
• 凶悪きょうあくatrocious
• 悪辣あくらつcrafty
• 腸の腐ったはらわたのくさったdepraved
• たちが悪いたちがわるいof bad character
• たちの悪いたちのわるいof bad character
• あくどいcrooked