azimuthal error

from The Collaborative International Dictionary of English v.0.48

Azimuthal \Az"i*muth`al\, a.
   Of or pertaining to the azimuth; in a horizontal circle.
   [1913 Webster]

   {Azimuthal error} of a transit instrument, its deviation in
      azimuth from the plane of the meridian.
      [1913 Webster]