The Collaborative International Dictionary of English v.0.48:

Athletic \Ath`let"ic\, a. [L. athleticus, Gr. ?. See Athlete.]
   1. Of or pertaining to athletes or to the exercises practiced
      by them; as, athletic games or sports.
      [1913 Webster]

   2. Befitting an athlete; strong; muscular; robust; vigorous;
      as, athletic Celts. "Athletic soundness." --South. --
      Ath*let"ic*al*ly, adv.
      [1913 Webster]