1. 
[syn: rascality, shiftiness, slipperiness, trickiness]
2.  the quality of requiring skill or caution; 
- Example: "these puzzles are famous for their trickiness"
The Collaborative International Dictionary of English v.0.48:
Trickiness \Trick"i*ness\, n.
   The quality of being tricky.
   [1913 Webster]
WordNet (r) 3.0 (2006):
trickiness
    n 1: the quality of being a slippery rascal [syn: rascality,
         shiftiness, slipperiness, trickiness]
    2: the quality of requiring skill or caution; "these puzzles are
       famous for their trickiness"