WordWeb Online

1. Exhibiting lack of respect; rude and discourteous
   "remarks disrespectful of the law"; "disrespectful in the presence of his parents"; "disrespectful toward his teacher"
    
2. Neither feeling nor showing respect
   - aweless, awless

See also: annihilating, contemptuous, contumelious, cynical, derisive, devastating, discourteous, disdainful, flip, gibelike, ignorant, immodest, impious, impudent, insolent, insulting, irreverent, jeering, mocking, offensive, sarcastic, scornful, snotty-nosed, taunting, undeferential, undutiful, withering

Antonym: respectful