The Collaborative International Dictionary of English v.0.48:

Prolixity \Pro*lix"i*ty\, n. [L. prolixitas: cf. F.
   prolixit['e].]
   The quality or state of being prolix; great length; minute
   detail; as, prolixity in discourses and writings. "For
   fulsomeness of his prolixitee." --Chaucer.
   [1913 Webster]

         Idly running on with vain prolixity.     --Drayton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

prolixity
    n 1: boring verbosity [syn: prolixity, prolixness,
         windiness, long-windedness, wordiness]