General synonyms:
* Abusive
* Insulting
* Disparaging
* Scornful
* Contemptuous
* Slandering
* Defamatory
* Demeaning
* Belittling
* Dismissive
More specific synonyms:
* Offensive: When the language is directly hurtful.
* Pejorative: When the language carries a negative connotation.
* Scurrilous: When the language is coarse and vulgar.
* Vituperative: When the language is harsh and bitter.
* Invective: When the language is strongly abusive and critical.
The best synonym will depend on the specific situation and the intended meaning.