Wordnet 3.0
NOUN (1)
1. 
 a tall and thin physique; 
The Collaborative International Dictionary of English v.0.48:
Lankiness \Lank"i*ness\, n.
   The condition or quality or being lanky.
   [1913 Webster]
WordNet (r) 3.0 (2006):
lankiness
    n 1: a tall and thin physique