The Collaborative International Dictionary of English v.0.48:

Millwork \Mill"work`\, n.
   1. The shafting, gearing, and other driving machinery of
      mills.
      [1913 Webster]

   2. The business of setting up or of operating mill machinery.
      [1913 Webster]

WordNet (r) 3.0 (2006):

millwork
    n 1: woodwork that has been machined at a mill