The Collaborative International Dictionary of English v.0.48:

Drill \Drill\, v. t. [imp. & p. p. Drilled; p. pr. & vb. n.
   Drilling.] [D. drillen to bore, drill (soldiers); probably
   akin to AS. pyrlian, pyrelian, to pierce. See Thrill.]
   1. To pierce or bore with a drill, or a with a drill; to
      perforate; as, to drill a hole into a rock; to drill a
      piece of metal.
      [1913 Webster]

   2. To train in the military art; to exercise diligently, as
      soldiers, in military evolutions and exercises; hence, to
      instruct thoroughly in the rudiments of any art or branch
      of knowledge; to discipline.
      [1913 Webster]

            He [Frederic the Great] drilled his people, as he
            drilled his grenadiers.               -- Macaulay.
      [1913 Webster]

WordNet (r) 3.0 (2006):

drilled
    adj 1: trained in a skill by repetitious practice; "well-drilled
           in military procedures"