Translation guide
The English word 'malicious' describes actions, intent, or people that are deliberately harmful or spiteful. In Japanese, there is no single perfect equivalent; the best choice depends on whether you are describing intent, a person, an action, or software.
He spread a malicious rumor.
The noun 'malice' or 'ill will.' Often used in phrases like 悪意を持って (with malice).
There was a sense of malice in his actions.
More colloquial, meaning 'mean-spirited' or 'spiteful.' Often used for petty malice.
She gave a malicious grin.
Means 'wicked' or 'evil,' implying a deeper, more sinister malice. Stronger than 悪意.
He devised a malicious plan.
Describing an action that is intentionally harmful.
Often used for malicious acts, especially in legal or formal contexts. Implies bad quality or nature.
Malicious harassment has become a problem.
Also works for actions, as in 'malicious act' (悪意のある行為).
That is a malicious act.
For petty or childish malicious acts.
He did something malicious.
Referring to malware, viruses, or harmful digital content.
The standard translation in IT contexts, as in 'malicious software' (悪意のあるソフトウェア).
Please be careful of malicious emails.
The loanword 'malware' is widely understood. Use this for the noun.
Means 'unauthorized' or 'fraudulent,' often used for malicious access or programs.
Describing someone who is habitually malicious.
悪意のある is neutral and can be used in formal or serious contexts. 意地悪な is more colloquial and often implies petty or childish malice. For cyber security, always use 悪意のある or 不正な.
malicious act (formal/neutral)
malicious joke (petty/mean)
The word 悪辣 (あくらつ) means 'crafty and malicious,' but it is very rare and literary. Stick to 悪意のある for most uses.
そのファイルはマルウェアに感染していた。
The file was infected with malware.
A malicious program was detected.
That person is malicious.
彼は悪人だ。
He is a malicious person.