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]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "curtness":
   abruptness, aggressiveness, bearishness, beastliness, bluntness,
   boorishness, brachylogy, brashness, brevity, briefness,
   brusqueness, brusquerie, churlishness, compactness,
   compendiousness, conciseness, concision, crispness, crustiness,
   dumbness, economy of words, gruffness, harshness,
   instantaneousness, laconicalness, laconism, littleness, lowness,
   muteness, nastiness, obmutescence, pauciloquy, pithiness,
   pointedness, quietness, quietude, reserve, roughness,
   sententiousness, severity, sharpness, short time, shortness,
   silence, sparingness of words, speechlessness, succinctness,
   summariness, surliness, taciturnity, terseness, transience,
   truculence, unloquaciousness, untalkativeness, wordlessness