Source : Webster's Revised Unabridged Dictionary (1913)

Nimbleness \Nim"ble*ness\, n.
   The quality of being nimble; lightness and quickness in
   motion; agility; swiftness.

Source : WordNet®

nimbleness
     n : the gracefulness of a person or animal that is quick and
         nimble [syn: {agility}, {legerity}, {lightness}, {lightsomeness}]