Source : Webster's Revised Unabridged Dictionary (1913)

Leveling \Lev"el*ing\, n. [Written also levelling.]
   1. The act or operation of making level.

   2. (Surveying) The art or operation of using a leveling
      instrument for finding a horizontal line, for ascertaining
      the differences of level between different points of the
      earth's surface included in a survey, for establishing
      grades, etc., as in finding the descent of a river, or
      locating a line of railroad.

   {Leveling instrument}. See {Surveyor's level}, under {Level},
      n.

   {Leveling staff}, a graduated rod or staff used in connection
      with a leveling instrument for measuring differences of
      level between points.