MALICIOUS meaning : 1. intended to harm or upset other people: 2. intended to cause damage to a computer system, or to…. Learn more. Malicious definition : Having the nature of or resulting from malice ; deliberately harmful; spiteful. Someone who is malicious enjoys hurting or embarrassing others. If you're writing a book about good and evil, you'll want to come up with a truly malicious character to do all the bad stuff. The meaning of MALICIOUS is having or showing a desire to cause harm to someone : given to, marked by, or arising from malice. How to use malicious in a sentence.