The Collaborative International Dictionary of English v.0.48:

Hairiness \Hair"i*ness\ (-[i^]*n[e^]s), n.
   1. The state of abounding, or being covered, with hair.
      --Johnson.
      [1913 Webster]

   2. The quality of being hairy.
      [PJC]

WordNet (r) 3.0 (2006):

hairiness
    n 1: the quality of having hair [syn: hairiness, pilosity]
         [ant: hairlessness]

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "hairiness":
   abstruseness, arduousness, bothersomeness, burdensomeness,
   complexity, complication, difficultness, difficulty, hardness,
   intricacy, laboriousness, onerousness, oppressiveness, rigor,
   rigorousness, ruggedness, strenuousness, toilsomeness, toughness,
   troublesomeness