Source : Webster's Revised Unabridged Dictionary (1913)

Discourteous \Dis*cour"te*ous\ (?; see {Courteous}, 277), a.
   [Pref. dis- + courteous: cf. OF. discortois.]
   Uncivil; rude; wanting in courtesy or good manners;
   uncourteous. -- {Dis*cour"te*ous*ly}, adv. --
   {Dis*cour"te*ous*ness}, n.

Source : WordNet®

discourteous
     adj 1: showing no courtesy; rude; "a distant and at times
            discourteous young" [ant: {courteous}]
     2: lacking social graces [syn: {ungracious}]