The Collaborative International Dictionary of English v.0.48:

Agility \A*gil"i*ty\, n. [F. agili['e], L. agilitas, fr.
   agilis.]
   1. The quality of being agile; the power of moving the limbs
      quickly and easily; nimbleness; activity; quickness of
      motion; as, strength and agility of body.
      [1913 Webster]

            They . . . trust to the agility of their wit.
                                                  --Bacon.
      [1913 Webster]

            Wheeling with the agility of a hawk.  --Sir W.
                                                  Scott.
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   2. Activity; powerful agency. [Obs.]
      [1913 Webster]

            The agility of the sun's fiery heat.  --Holland.
      [1913 Webster]

WordNet (r) 3.0 (2006):

agility
    n 1: the gracefulness of a person or animal that is quick and
         nimble [syn: agility, legerity, lightness,
         lightsomeness, nimbleness]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "agility":
   acuity, acuteness, alacrity, alertness, attention, attentiveness,
   brightness, briskness, dispatch, expedition, expeditiousness,
   featliness, keenness, lightness, nimbleness, promptitude,
   promptness, punctuality, quickness, readiness, sharpness,
   sleeplessness, smartness, speediness, spryness, swiftness,
   wakefulness