Source : Webster's Revised Unabridged Dictionary (1913)

Volubility \Vol`u*bil"i*ty\, n. [L. volubilitas: cf. F.
   volubilit['e].]
   The quality or state of being voluble (in any of the senses
   of the adjective).

Source : WordNet®

volubility
     n : the quality of being facile in speech and writing [syn: {fluency},
          {articulateness}]