Wordnet 3.0
NOUN (1)
1. 
 the quality of being intricate and compounded; 
- Example: "he enjoyed the complexity of modern computers"[syn: complexity, complexness]
The Collaborative International Dictionary of English v.0.48:
Complexness \Com"plex`ness\, n.
   The state of being complex; complexity. --A. Smith.
   [1913 Webster]
WordNet (r) 3.0 (2006):
complexness
    n 1: the quality of being intricate and compounded; "he enjoyed
         the complexity of modern computers" [syn: complexity,
         complexness] [ant: simpleness, simplicity]