The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

WordNet (r) 3.0 (2006):

discourteously
    adv 1: in an impolite manner; "he treated her impolitely" [syn:
           impolitely, discourteously, rudely] [ant:
           courteously, politely]