The Collaborative International Dictionary of English v.0.48:

Curtness \Curt"ness\, n.
   The quality of bing curt.
   [1913 Webster] curtsey

WordNet (r) 3.0 (2006):

curtness
    n 1: an abrupt discourteous manner [syn: abruptness,
         brusqueness, curtness, gruffness, shortness]