The adjective malicious means showing malice or intentional desire to cause harm to someone.

Synonyms are bad, cruel, spiteful, or malevolent.

The word origins from Old French (mid 13th century) malicios meaning “showing ill will, spiteful, wicked” (Modern French malicieux). It also comes from Latin malitiosus meaning “wicked, malicious” from malitia meaning “badness, ill will, spite”. In legal use (early 14c., Anglo-French), it means “characterized by malice prepense”.

Her malicious intentions to were obvious so she immediately got caught.

If you see a malicious malware on your computer, you have to remove it immediately.

He was charged with malicious destruction of property.