* abusive: using insulting or offensive language
* vile: morally reprehensible or disgusting
* base: low, mean, or dishonorable
* libellous: containing false and damaging statements
Essentially, something scurrilous aims to damage someone's reputation or character through untrue and harmful words or actions.
Example:
* "The politician's speech was filled with scurrilous attacks on his opponent, accusing her of corruption and incompetence."