Source : Webster's Revised Unabridged Dictionary (1913)

Tactic \Tac"tic\, Tactical \Tac"tic*al\, a. [Gr. ?. See
   {tactics}.]
   Of or pertaining to the art of military and naval tactics. --
   {Tac"tic*al*ly}, adv.

Source : WordNet®

tactically
     adv : with regard to tactics; "the tactically useful province is
           still firmly in the rebels' hands"