scurrilous

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Given to the use of vulgar, coarse, or abusive language.
• adjective Expressed in vulgar, coarse, or abusive language.
• adjective Of a malicious or slanderous nature; defamatory.

from The Century Dictionary.

• Using or given to the use of low and indecent language; scurril; indecently or grossly abusive or railing.
• Containing low indecency or abuse; foul; vile: as, scurrilous language.
• Opprobrious; abusive; offensive.
• Synonyms Ribald, blackguard, indecent, coarse, vulgar, gross.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Using the low and indecent language of the meaner sort of people, or such as only the license of buffoons can warrant.
• adjective Containing low indecency or abuse; mean; foul; vile; obscenely jocular.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective of a person given to vulgar verbal abuse; foul-mouthed
• adjective of language coarse, vulgar, abusive, or slanderous

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective expressing offensive reproach