Source : Webster's Revised Unabridged Dictionary (1913)

Mobility \Mo*bil"i*ty\, n. [L. mobilitas: cf. F. mobilit['e].]
   1. The quality or state of being mobile; as, the mobility of
      a liquid, of an army, of the populace, of features, of a
      muscle. --Sir T. Browne.

   2. The mob; the lower classes. [Humorous] --Dryden.

Source : WordNet®

mobility
     n : the quality of moving freely [ant: {immobility}]