资料来源 : Webster's Revised Unabridged Dictionary (1913)

Overhead \O`ver*head"\, adv.
   Aloft; above; in or attached to the ceiling or roof; in the
   story or upon the floor above; in the zenith.

         While overhead the moon Sits arbitress.  --Milton.

   Note: Also used adjectively; as, an overhead crane, gear,
         etc.

   {Overhead engine}, a vertical steam engine in which the
      cylinder stands above the crank.

   {Overhead work}, a general term in manufactories for
      countershafting and gearing, when overhead.